ENGIN. 
LIBRARY 


B    3    mi 


EN1ARY 
INE  SHOP 
1ACTICE 


;ER 


GIFT  OF 
Mr.  &  Mrs.  A.  Dubecker 


//  /J — / 


^-  >  c  V//-" 
•  tj,      >M- 


ELEMENTARY 
MACHINE  SHOP 
PRACTICE  AS..SB: 


BY 


T.  J.  PALMATEER 

// 
INSTRUCTOR  IN  MACHINE  SHOP  PRACTICE 

LELAND  STANFORD  JUNIOR  UNIVERSITY 
PALO  ALTO,  CALIFORNIA 


THE  MANUAL  ARTS  PRESS 

PEORIA,  ILLINOIS 


Library 

Copyright,  1918 

Copyright,  1920 

T.  J.  PALMATEER 

22D22 


Printed  in  the  United  States  of  America 

2 


PREFACE 

The  first  edition  of  Elementary  Machine  Shop  Practice 
was  intended  as  an  instruction  book  for  shop  use  only.  The 
revised  edition  contains  several  additional  pages  of  new 
matter  which  gives  it  a  wider  range  of  usefulness. 

To  get  the  best  results  from  the  book  the  problems  de- 
scribed should  be  made,  because  the  information  may  then 
be  directly  applied  while  the  student  is  at  work  in  the  shop. 
But  in  schools  where  problems  of  different  design  are  used, 
or  if  machine  parts  are  made,  it  is  believed  the  book  will  be 
a  great  help  as  a  reference.  It  may  also  be  used  to  good 
advantage  in  classes  of  technical  English. 

In  case  it  is  considered  advisable  to  devote  to  the  elemen- 
tary operations  less  time  than  would  be  necessary  to  complete 
the  problems  presented  herein,  very  good  results  can  be  ob- 
tained if  the  student  will  read  all  of  the  instructions  carefully 
and  then  do  only  such  problems  as  the  instructor  considers 
necessary. 

The  instructions  here  given  are  not  intended  as  fixed  rules, 
for  it  is  recognized  that  some  of  the  operations  may  be  done 
by  other  methods  with  equally  good  results. 

Many  thanks  are  due  to  Prof.  E.  P.  Lesley  and  H.  P.  Miller, 
Jr.,  for  their  helpful  assistance  in  the  preparation  of  this  book ; 
and  to  the  following  manufacturers  for  the  electrotype  illus- 
trations: Smith  &  Mills  Co.,  Sibley  Machine  Co.,  Lodge  & 
Shipley  Machine  Tool  Co.,  The  Cincinnati  Milling  Machine 
Co.,  and  the  Brown  &  Sharpe  Co. 


CONTENTS 

PAGE 

Introduction 7 

CHAPTER  I — VISE  WORK 

Problem  1 — Surfacing  a  Cast-Iron  Block 9 

Chipping  —  Sharpening  Chisels  —  Files  and  Filing  — 
Scraping — Use  of  Surface  Plate — Grinding — Scraper 
— Oilstoning  Scraper. 

CHAPTER  II — SHAPER  WORK 
Description  of  Shaper 18 

Problem  2 — Planing  One  Surface  Square  with  Another 19 

Clamping  Work  in  Vise — Roughing  Cut — Setting  Fin- 
ishing Tool — Rate  of  Feed — Resetting  Work — To  Pre- 
vent Corners  from  Breaking. 

Problem  3 — Planing  One  Surface  Parallel  with  Another  and  Planing 

Angles    26 

Roughing  Out  Angles — Setting  the  Head,  Clapper  Box, 

and  Tool — Finishing  Angles. 

Questions  31 

CHAPTER  III — DRILLING 
Description  of  Drill  Press 32 

Problem  A — Drilling  and  Tapping 34 

Laying  Out  Centers  of  Holes — Holding  the  Work — 
Selecting  Drill — How  Drills  are  Ground. 

CHAPTER  IV— TAPS  AND  DIES 

Taps  and  Dies 40 

Use  of  Taps — Hand  Tapping — Machine  Tapping — Use 
of  Dies. 

CHAPTER  V— LATHE  WORK 

Description  of  Lathe 46 

Parts  of  Lathe 48 

Problem  5— Fitting  Shaft  to  Collar 49 

Centering — Placing  Work  in  Lathe — Finishing  End  of 
Shaft  —  Turning  Shaft  —  Speed  of  Lathe  —  Adjusting 
Lathe  to  Turn  Straight — Filing. 

Problem  6 — Turning  and  Threading  Taper  Shaft 56 

Use  of  Lubricant — Cutting  Recess — Size  and  Shape  of 
Threads — Grinding  Tool — Setting  Tool — How  Lathe  Is 
Geared — Why  Feed  should  be  Disconnected — Finishing 
Side  of  Thread— How  to  Reset  the  Tool. 

5 


CONTENTS 

PAGE 

Problem  7 — Boring  and  Turning  Cast-Iron 65 

Use  of  Lathe  Chucks — Centering  Work  in  Chuck — Rough 
Turning — Use  of  Flat  Drill — Use  of  Boring  Bar — Why 
Reamers  are  Used — Boring  and  Reaming  Hole — Inside 
Threading — Finishing  Taper — Drilling  and  Reaming — 
Advantage  of  Rose  Reamer — Use  of.  Mandrel,  or 
Arbor — Making  Mandrel — Threading — Finishing  Out- 
side Cast-Iron — Micrometer  Caliper — How  to  Read  the 
Micrometer  —  Knurling  —  Turning  Tool  for  Brass — 
Drilling  Brass. 

Problem  8— Brass  Plumb  Bob  with  Steel  Point 85 

CHAPTER  VI 

Survey  of  Lathe  and  Shaper  Tools 88 

Shape  of  Tool  s — Steel  for  Cutting  Tools — How  to 
Determine  the  Difference  between  High-Speed  Steel 
and  Carbon  Steel — How  to  Determine  the  Hardness  of 
Tools— Rate  of  Feed— Depth  of  Cut. 

Questions  91 

CHAPTER  VII— MILLING  MACHINE  WORK 
Description  of   Milling  Machines 92 

Problem  9 — Milling  a  Square  Casting 94 

Milling  Machine  Vise — Clamping  the  Work — The  Cut- 
ter— The  Arbor — Direction  of  Cutter  Rotation — Cutter 
Speed — Direction  of  Feed — Roughing  Cut — Finishing 
Cut. 

Problem  10 — Milling  a  Concave  Surface,  Recess,  etc 99 

Use  of  End  Mill— Depth  of  Cut— Speed  of  Cutter— Mill- 
ing Slot  —  Gang  Milling  —  Groove  Cutting  —  Forming 
Cutter. 

Dividing  Head  and  Tail-Stock 103 

Index  Plate — Index  Crank — Index  Pin — Indexing — 
Examples  of  Use  for  Dividing  Head. 

Spur  Gears  and  Rack 105 

Terms  Used — Shape  of  Tooth  Cutter — Rules  for  Com- 
puting Spur  Gears. 

Problem  11  —Gear  Cutting 110 

Selecting  Cutter — Mounting  Cutter — Centering  Cutter — 
Mounting  Gear  in  Machine — Depth  of  Cut — Setting 
Index  Crank — Setting  the  Sector. 

Cutting  a  Rack ; 112 

Questions 115 

Index   .  .118 


INTRODUCTION 

This  manual,  while  it  does  not  cover  the  whole  field  of 
machine  shop  work,  should  meet  the  requirements  of  begin- 
ners in  general  machine  shop  practice.  Its  main  object  is  to 
reduce  as  much  as  possible  the  time  required  to  bring  a  student 
with  no  previous  shop  experience  to  the  point  where  he  is 
able  to  do  some  real  work.  For  this  purpose  the  problems 
have  been  designed  with  the  view  of  giving  the  student  the 
maximum  amount  of  information  in  the  small  amount  of  time 
usually  allowed  for  this  purpose.  The  repetition  of  operations 
has  therefore  been  avoided  wherever  it  was  considered  advis- 
able and  the  time  lost  in  simply  cutting  off  metal  has  been 
reduced  to  the  minimum. 

The  instructions  given  refer  mainly  to  the  cutting  of  metal, 
since  this  usually  gives  the  most  trouble  to  beginners.  Little 
attempt  has  been  made  to  describe  the  mechanism  of  the 
different  machines  because  it  varies  so  much  with  the  type 
and  make,  and  besides  is  easily  understood  by  the  average 
student. 

It  is  assumed  that  beginners  will  receive  oral  instruction 
on  the  manipulation,  such  as  shifting  the  belt,  handling  the 
feed  control,  etc.,  of  the  different  machines.  It  is  suggested 
that  the  instructor  give  a  practical  demonstration  by  doing 
enough  work  on  the  problems  to  show  the  tools  necessary 
and  how  they  are  used. 

The  machine  speeds  for  the  different  operations  as  indi- 
cated in  this  book  are  only  approximately  correct,  since  the 
actual  cutting  speed  of  the  tool  in  feet-per-minute  varies  with 
the  size  and  kind  of  machine  used.  The  instructor  is  expected 
to  designate  the  proper  speeds,  altho  the  belt  connections  given 
herein  will  generally  be  close  enough  for  beginners. 


8  INTRODUCTION 

In  learning  machine  shop  work  the  student  goes  thru 
what  might  be  called  two  stages,  i.e.,  elementary  and  advanced. 
In  the  elementary  or  beginning  stage  it  will  be  necessary  for 
him  to  acquire  considerable  knowledge  or  theory.  After  the 
fundamentals  have  been  mastered,  practice  appears  to  be  the 
more  important  factor. 

Since  the  progress  that  a  beginner  makes  depends  largely 
upon  the  time  required  to  learn  the  fundamentals,  it  is  impor- 
tant that  he  study  very  carefully  the  directions  for  making 
the  problems. 


ELEMENTARY 
MACHINE  SHOP  PRACTICE 


CHAPTER  I 
VISE  WORK 

Altho  most  of  the  metal  cutting  in  the  machine  shop  can 
be  done  by  machine,  it  is  sometimes  necessary,  even  in  the 
most  modern  shops,  to  do  some  of  it  by  hand.  In  order  to  give 
the  student  practice  in  this  hand,  or  vise  work,  the  sides  A  and 
B  of  the  cast-iron  block,  Fig.  1,  are  to  be  finished  by  chipping, 
filing  and  scraping. 

Problem  1. — Surfacing  a  Cast-Iron  Block. 

A  A 


•     --T     ' 

B     ? 
..1.     . 

B 

-  ---  -2ft'-  ---  • 


FIG.  1 


Sequence  of  Operations  : 

1.  Chip  and  file  side  A. 

2.  Scrape  side  A  true  to  a  surface  plate. 

3.  Chip  and  file  side  B  square  with  A. 

4.  Scrape  side  B  true  to  surface  plate. 

Chipping.  —  The  original  surface  of  cast  iron  is  very  hard 
for  a  depth  of  about  1/64"  and  is  almost  impossible  to  file.  It 
is  therefore  necessary  to  remove  this  hard  scale  with  chisels 
before  starting  to  file. 

For  this  sort  of  chipping,  cape  and  flat  chisels,  Figs.  2  and 
3,  respectively,  are  used. 


10 


VISE  WORK 


Parallel  grooves  are  first  cut  in  the  surface  as  shown  in 
Fig.  4.  These  grooves  must  be  just  deep  enough  to  get  under 
the  scale,  i.  e.,  not  less  than  1/32"  nor  more  than  1/16"  deep. 


FIG.  4 

When  they  have  been  cut  to  within  1/4"  of  the  end,  the  direc- 
tion of  chipping  should  be  reversed  to  prevent  breaking  out  the 
cast  iron  at  the  corner. 

The  grooves  should  be  uniformly  spaced,  in  this  case,  about 
1/4"  to  5/16"  apart.  On  heavier  work,  where  larger  chisels 
are  necessary,  the  grooves  are  cut  further  apart.  Generally 
the  distance  between  the  grooves  should  be  about  equal  to  the 
width  of  the  cape  chisel  used. 

Care  should  be  taken  not  to  chip  one  portion  of  the  surface 
deeper  than  another;  the  more  uniform  the  grooves  the  less 
will  be  the  filing  required  to  make  the  surface  straight.  The 
metal  ridges  are  chipped  off  with  the  flat  chisel  shown  in  Fig.  3. 

Sharpening  the  Chisels. — To  do  good  work  the  chisels  must 
be  kept  sharp  by  grinding,  on  a  fine  grinding  wheel.  Care 
should  be  taken  not  to  hold  them  too  hard  against  the  wheel, 
thus  drawing  the  temper. 

If  the  chisels  are  to  be  used  for  very  light  cuts,  say  1/64" 
deep,  the  cutting  edge  may  be  ground  to  a  smaller  angle  than 
is  shown  in  Figs.  2  and  3. 


FILES  AND  FILING 


11 


Files  and  Filing 

Files. — While  there  is  a  large  variety  of  shapes  and  sizes  of 
files  manufactured,  only  the  ones  to  be  used  on  these  problems 
will  be  described.  Students  desiring  further  information  on 
files  should  consult  the  catalog  of  some  standard  file  manu- 
facturer. 

Files  are  designated  by  their  size,  type,  and  the  coarseness 
or  cut  of  their  teeth. 

The  size  refers  to  the  distance  from  the  end  of  the  file  to 
the  point  where  the  tang  begins,  Fig.  5. 

Th^  type  refers  to  the  general  shape  of  the  file.  Those 
most  commonly  used  in  a  machine  shop  are  the  mill,  flat,  hand, 
square,  round  and  half-round  files. 

The  mill,  flat  and  hand  files  are  very  similar  in  shape,  but 
differ  from  one  another  in  detail. 


Plat 


Hand 


FIG.  5 

The  mill  file  is  uniform  in  thickness,  tapered  in  width  and  is 
single  cut,  i.  e.,  has  only  one  course  of  teeth.  It  is  used  principally 
for  lathe  work. 

The  flat  file  is  tapered  in  both  width  and  thickness  and  is 
double  cut.  It  is  intended  mainly  for  general  use  and  is  not  suit- 
able for  lathe  work. 


12  VISE  WORK 

The  hand  file  is  uniform  in  width,  tapered  in  thickness  and 
double  cut.  It  is  a  little  wider  than  the  mill  and  flat  file  and  has 
one  safe  edge,  i.  e.,  one  edge  without  teeth. 

The  advantage  of  this  safe  edge  is  that  the  file  may  be  used 
close  up  to  a  square  corner  without  cutting  in  at  the  side.  This  file 
is  preferred  by  machinists  for  flat  surfaces,  altho  the  flat  file 
may  also  be  used  for  such  work.  An  edge  of  a  flat  file  may  be 
made  safe  by  grinding  off  the  teeth. 

The  common  square  file  is  tapered  and  double  cut.  It  is  used 
for  filing  square  and  rectangular  holes  and  on  square  corners. 
For  this  kind  of  work  one  edge  should  be  safe. 

The  common  round  file  is  tapered  and  double  cut..  It  is  used 
for  filing  round  holes,  concave  surfaces,  etc. 

The  half-round  file  is  tapered  and  double  cut.  It  is  used  on 
large  round  holes,  concave  surfaces  and  acute  angles.  The  latter 
use  is  illustrated  in  Fig.  30,  page  30. 

The  coarseness  or  cut  of  a  file  refers  to  the  spacing  of  the  teeth. 
The  three  different  spacings,  or  cuts,  in  common  use  are  the 
bastard,  second  cut  and  smooth.  Practically  all  of  the  common 
files  may  be  obtained  in  any  of  these  three  cuts. 

Filing.— Having  removed  the  scale  on  the  cast  iron  block 
with  chisels,  the  surface  should  be  filed  approximately  straight 
with  a  hand  bastard  file.  If  a  hand  file  is  not  available  a  flat 
file  may  be  used. 

In  the  first  rough  filing,  a  full  stroke  of  the  file  is  used,  but 
as  the  surface  approaches  a  true  plane  this  may  be  changed  to 
a  short  stroke.  A  short  stroke  makes  it  easier  to  control  the 
file.  Rocking  the  file  should  be  avoided  as  it  causes  the  edges 
and  corners  of  the  work  to  be  filed  lower  than  the  center. 

To  test  the  straightness  of  the  surface  being  filed,  the  edge 
of  a  steel  rule  is  held  on  it  in  several  positions. 

When  filing  work  of  this  kind  it  is  advisable  to  file  in  differ- 
ent directions,  i.  e.,  parallel  with  one  edge,  crosswise  and 
diagonally. 

The  teeth  of  all  files  are  made  to  cut  on  the  forward  stroke. 


FILING  13 

For  this  reason  the  pressure  should  be  relieved  on  the  return 
or  backward  stroke. 

It  will  be  noticed  upon  sighting  along  the  edge  of  a  hand 
file  that  the  thickness  does  not  taper  uniformly,  both  sides 
being  slightly  convex.  The  curves  are  .supposed  to  be  uniform, 
but  the  warping  that  occurs  in  tempering  causes  greater  con- 
vexity at  one  place  than  another.  By  using  the  file  at  the  point 
of  greatest  convexity  and  by  giving  it  a  short  stroke  the  work 
may  be  filed  straight  even  tho  the  file  does  rock  a  little.  If 
the  file  is  warped  to  the  extent  that  one  side  is  slightly  concave 
it  will  be  impossible  to  file  the  work  straight  with  that  side. 

After  the  surface  has  been  filed  straight  with  the  coarse  or 
bastard  file  it  is  finished  smoother  with  a  hand  or  flat  smooth  file. 
Instead  of  filing  in  different  directions,  as  in  rough  filing,  the 
strokes  should  be  parallel  with  one  edge  of  the  work.  This 
causes  all  the  scratches  or  lines  made  by  the  file  to  be  parallel, 
giving  the  surface  a  better  appearance.  If  it  is  to  be  scraped, 
as  in  this  case,  this  will  also  make  it  much  easier. 

When  filing  cast  iron  the  file  dust  should  never  be  brushed 
off  the  work  with  the  hand,  as  the  hand  deposits  more  or  less 
grease,  causing  the  file  to  slip  and  dull  quickly.  Machinists 
usually  blow  off  the  dust.  When  filing  wrought  iron  or  steel, 
oil  or  grease  does  no  harm,  in  fact  oil  is  sometimes  used  to  pro- 
duce a  smooth  finish. 

Scraping 

After  the  surface  A  has  been  filed  smooth  and  approxi- 
mately straight,  it  is  finished  to  a  plane  surface  with  a  surface 
plate  and  scraper. 

Use  of  Surface  Plate. — To  locate  the  high  places  on  a  flat 
surface  a  surface  plate,  Fig.  6,  is  used.  The  size  of  the  plate  is 
usually  a  little  larger  than  the  surface  being  scraped.  The  side 
A  is  first  covered  with  a  thin  film  of  paint  made  of  lamp  black 
and  lard  oil.  It  is  then  placed  in  contact  with  the  surface  to  be 


14 


VISE  WORK 


_    _     _      A"_  _ 

f-\  —  »j 


FIG.  6 


scraped  and  moved  around  over  it,  marking  the  high  spots. 

The  paint  should  be  spread  on  the  plate  with  the  finger  tips 
and  just  thick  enough  to  cover  it.  If  waste  or  cloth  is  used, 

t fc          lint  is  deposited  on  the  plate  and 

interferes  writh  the  marking.  If 
it  is  spread  on  too  thick,  the  low 
places  will  be  marked  as  well  as 
the  high  ones. 

It  is  very  easy  to  locate  the 
high  spots  if  the  work  is  a  little 
concave,  but  if  a  little  convex  the 
plate  is  apt  to  rock  when  moved 
over  the  surface,  thus  marking 
the  low  as  well  as  the  high  spots. 
This  makes  it  very  important  to 
use  as  little  paint  on  the  surface 
plate  as  possible,  and  to  move  it 
over  the  work  without  rocking. 

After  locating  the  high  spots  the  scraper  is  used  on  them 
and  the  work  again  tested  with  the  plate.  These  operations 
are  repeated  until  the  surface  is  true. 

Use  of  the  Scraper. — In  use  the  scraper  is  held  firmly  with 
both  hands  at  about  the  angle  shown  in  Fig.  7.  The  cutting  is 
done  by  holding  it  down  hard  on  the  work  and  moving  it  for- 
ward in  the  direction  indicated  by  the  arrow.  If  the  handle  is 
held  too  high  or  too  low  the  scraper  will  not  cut  satisfactorily. 
A  little  practice  will  be  required  before  a  beginner  can  properly 
control  it. 

When  using  the  scraper  it  will  be  noticed  that  it  has  a 
tendency  to  chatter,  causing  a  slightly  wavy  line  cut  instead  of 
a  smooth  one.  If  all  the  scraping  is  done  in  one  direction  these 
chatter  marks  become  deeper.  This  may  be  .avoided  by  vary- 
ing the  direction  of  the  scraping  a  little  after  each  marking 
with  the  surface  plate, 


GRINDING  THE  SCRAPER 


15 


The  scraper  is  usually  made  from  an  old  10"  file  by  grind- 
ing off  the  teeth  and  forging  it  to  the  shape  shown  in  Fig.  8. 


FIG.  7 


Grinding  the  Scraper. — After  forging  and  hardening,  the 
scraper  is  ground  straight  on  the  side  B,  Fig.  8,  and  slightly 
convex  across  the  end  A.  If  the  latter  edge  is  curved  too  much, 
the  scraper  will  take  too  narrow  a  cut,  while  if  it  is  perfectly 
straight  the  cut  will  be  so  wide  that  it  will  not  be  smooth.  The 
scraper  should  be  ground  so  as  to  take  a  cut  about  1/4"  or 
wider. 

The  edge  C  should  be  ground  at  right  angles  with  the 
center  line  of  the  scraper. 

CAUTION. — The  scraper  is  made  of  carbon  steel  and  is 
tempered  very  hard.  Beginners  are  therefore  cautioned  not  to 
draw  the  temper  at  the  cutting  edge  by  grinding  it  too  fast. 
This  often  happens  without  being  noticed  so  that  the  beginner 
is  unable  to  understand  why  his  scraper  will  not  cut. 

Oilstoning  the  Scraper. — The  grinding  wheel  produces  a 
somewhat  rough  cutting  edge  which  must  be  oilstoned  before 
the  scraper  will  cut  smoothly.  This  oilstoning  is  done  by 
moving  the  end  and  the  sides  of  the  scraper  alternately  over 
the  surface  of  a  flat  oilstone. 


16 


VISE  WORK 


When  oilstoning  the  end  it  may  be  held  vertically,  Fig.  9, 
or  at  a  slight  angle,  as  in  Fig.  10.  If  held  at  an  angle  the 
sharpening  is  done  a  little  quicker  and  the  edge  will  be  slightly 


B 

B 

\ 

' 

F 

^   r 

._, 

L    

Fir,  8 


FIG.  9 


FIG.  10 


beveled.  Such  an  edge  will  cause  less  chattering  than  the  one 
obtained  by  oilstoning  as  in  Fig.  9.  When  one  edge  has  been 
sharpened  the  scraper  is  turned  over  and  the  other  edge 
sharpened  in  the  same  manner. 

Fig.  11  shows  the  correct  position  for  oilstoning  the  side. 
The  handle  should  not  be  raised,  as  in  Fig.  12,  as  this  would 
take  off  the  sharp  edge.  A  fine  wire  or  feather  edge  is  pro- 
duced, no  matter  how  hard  the  scraper  is  tempered.  To  take 
advantage  of  it,  the  scraper  should  be  oilstoned  on  the  side  last 


OILSTONING  THE  SCRAPER 


17 


if  it  is  to  cut  on  the  forward  stroke,  as  in  Fig.  7,  and  on  the 
end  last  if  it  is  to  cut  on  the  draw  stroke. 


FIG.  11 


FIG.  12 

In  order  to  do  good  work  the  scraper  must  be  kept  very 
sharp.  It  will  be  necessary  to  oilstone  it  several  times  while 
scraping  the  surface  of  this  problem. 

When  the  scraper  has  been  repeatedly  oilstoned  so  that  the 
cutting  edges  are  worn  off,  the  end  should  be  reground  on  the 
grinding  wheel  to  the  original  shape,  as  shown  at  C  in  Fig.  8. 

Finishing  Side  B. — After  side  A  of  Problem  I  has  been 
finished,  the  side  B  is  squared  with  A  by  the  same  process, 
i.  e.,  by  chipping,  riling  and  scraping. 

If  B  is  very  much  out  of  square  with  A,  one  side  of  B  may 
be  chipped  a  little  deeper  than  the  other.  In  doing  this  it  will 
be  better  to  take  several  light  cuts  with  the  cape  chisel  than  to 
try  to  remove  too  much  metal  in  one  cut.  Too  deep  a  cut  will 
cause  the  edge  of  the  chisel  to  break. 


CHAPTER  II 
SHAPER  WORK 

Description  of  Shaper. — The  size  of  a  shaper  is  usually 
designated  by  its  maximum  length  of  stroke ;  as,  a  16"  or  a 
20"  shaper. 

The  shaper  shown  in  Fig.  13  has  a  four-step  cone  drive 
with  back  gears  giving  eight  speeds.  Two  sides  as  well  as  the 
top'of  the  table  are  provided  with  slots  for  clamping  work  that 
is  too  large  to  be  held  in  the  vise. 

The  head  is  graduated  at  R  so  that  it  may  be  set  at  any 
desired  angle,  as  in  Fig.  25,  page  28.  The  clapper  box  M  may 
be  turned  to  various  positions  by  loosening  the  hexagonal-head 
screw  N.  The  heavy  casting  BBB  has  a  reciprocating  motion 
and  is  called  the  ram.  The  jack  D  supports  the  outer  end  of 
the  table.  The  lever  K  controls  the  back  gears. 

The  table  may  be  raised  or  lowered  by  means  of  a  hand 
crank  on  shaft  E  shown  at  the  end  of  the  cross-rail.  By 
placing  this  crank  on  the  shaft  immediately  above  it  the  table 
may  be  fed  horizontally  by  hand. 

The  automatic  table  feed  is  started,  stopped,  or  reversed 
by  means  of  a  small  knobbed  pin  F  which  engages  the  ratchet 
gear  at  the  end  of  the  cross-rail.  The  rate  of  feed  is  varied, 
either  while  the  machine  is  idle  or  in  motion,  by  changing 
the  position  of  a  large  knobbed  pin  on  the  disc  near  the  driv- 
ing cone.  The  squared  shaft  above  this  disc  is  used  for 
changing  the  length  of  the  stroke.  The  position  of  the  stroke 
is  changed  by  loosening  the  lever  H  on  top  of  the  ram  and 
turning  the  squared  shaft  J  shown  near  the  head  of  the  ram. 

The  vise  L  is  used  for  holding  small  work.  The  jaws  are 
opened  and  closed  by  means  of  a  hexagon-headed  screw.  The 
square-head  screw  S  is  for  clamping  the  movable  jaw  to  the 

base. 

18 


THE  SHAPER 


19 


The  machine  is  started  and  stopped  independent  of  the 
countershaft,  by  means  of  a  friction  clutch  in  the  driving  cone 
operated  by  lever  O. 


H 


B 


FIG.  13.    TWENTY-INCH  SHAPER 

Problem  2. — Planing  One  Surface  Square  With  Another. 

A  A 


B 


t- -2f-~J  h -5" 1 

FIG.  14 

Sequence  of  Operations: 

1.     Clamp  in  shaper  vise  and  plane  side  D  square  with  A 
and  parallel  with  B, 


20 


SHAPER  WORK 


2.  Plane  the  ends  E  and  F  square  with  the  sides  A,  B, 
and  D. 

In  taking  up  the  problem  on  the  shaper  it  is  assumed  that 
the  sides  A  and  B  of  the  cast-iron  block  in  Fig.  14  have  been 
finished  true  and  square  in  the  vise.  The  other  sides  are  to  be 
finished  on  the  shaper  to  the  dimensions  given. 

It  may  be  somewhat  easier  to  follow  the  instructions  if  the 
six  sides  of  the  block  are  lettered  with 
a  piece  of  chalk  to  correspond  with  the 
drawing. 

First  lay  off  the  width  of  the  side 
C  with  a  scriber  and  combination 
square,  as  shown  in  Fig.  15,  marking  a 
line  2  5/8"  from  the  side  B  and  parallel 
with  it.  In  order  to  make  the  scriber 
marks  plainly  visible  the  surface  should 
be  chalked.  This  is  especially  neces- 
sary when  the  hard  scale  has  not  been 
removed. 


FIG.  15 


Clamping  the  Work  in  Vise. — The  work  is  clamped  in  the 

shaper  vise  with  the  finished  side  B  resting  on  the  base  and 

with  the  side  A  against  the  stationary  jaw  of  the  vise,  as  in 

Fig.  16.    A  piece  of  paper  should  be  kept  under  each  end  of  B. 

»     D    2 


FIG.  16 


The  clamping  bolt  J  may  be  left  loose  until  the  jaw  is  close 
to  the  work,    It  should  then  be  tightened  so  that  as  the  jaw  is 


CLAMPING  WORK  IN  VISE 


21 


screwed  up  against  the  work  it  will  not  be  raised  off  the  base 
of  the  vise. 

The  narrow  metal  strip  shown  at  H  should  be  about  1/16" 
x  1/2"  x  6".  It  is  used  so  that  when  the  vise  is  tightened  the 
pressure  on  the  block  will  be  about  at  the  center.  This  holds 
the  side  A  tight  against  the  solid  jaw.  By  rapping  side  D  with 
a  hammer,  B  is  forced  down  on  the  base  of  the  vise  until  the 
paper  at  both  ends  is  tight.  The  work  is  now  ready  for  the 
roughing  cut. 

n 


••-.J 


*- 


-V 


FIG.  17 


FIG.  18 


Roughing  Cut. — This  is  taken  with  a  tool  or  bit  similar  to 
the  one  used  on  the  lathe,  but  which  has  less  clearance  since  it 
cuts  along  a  straight  line.  The  lathe  tool  holder  is  sometimes 
used  on  the  shaper,  but  a  regular  shaper  tool  holder,  Fig.  17, 
is  preferred.  The  latter  has  an  adjustable  head  or  clamp  so 
that  the  tool  may  be  turned  at  different  angles.  The  piece  of 
tool  steel  used  in  such  a  holder  should  always  be  longer  than 
the  diameter  of  the  head,  otherwise  it  will  not  be  held  firmly. 

Depth  of  Cut. — The  depth  of  the  roughing  cut  depends 
mainly  upon  the  size  of  the  machine  and  the  amount  of  metal 


22  SHAPER  WORK 

to  be  removed.  If  1/8"  is  to  be  cut  off  take  a  little  more 
than  half  that  amount  the  first  cut. 

Rate  of  Feed. — This  also  depends  largely  upon  the  size  of 
the  machine.  With  large  and  heavy  machines  deep  cuts  may 
be  taken  and  coarse  feeds  used. 

If  a  small  shaper  is  used,  as  is  generally  the  case  with  work 
of  this  sort,  the  rate  of  feed  with  a  cut  about  1/8"  deep,  may  be 
about  1/64".  With  a  cut  only  1/16"  deep  the  feed  may  be 
increased  to  1/32"  per  stroke. 

Finishing  Cut. — The  finishing  tool,  Fig.  18,  is  forged  from 
a  piece  of  carbon  steel.  Care  should  be  used  in  grinding  it  not 
to  draw  the  temper.  The  advantage  of  using  carbon  steel 
instead  of  high-speed  steel  for  this  tool  is  that  it  makes  a 
smoother  finishing  cut  and  is  cheaper  and  easier  to  forge.  The 
cutting  edge  should  be  ground  as  straight  as  possible.  It  may 
be  a  little  convex  but  never  concave.  The  clearance  angle  B 
should  be  about  10°  or  15°. 

Setting  the  Finishing  Tool. — In  order  ,to  take  a  smooth 
finishing  cut,  the  tool  should  be  set  with  the  cutting  edge 
parallel,  or  nearly  so,  with  the  surface  to  be  planed.  This  is 
done  by  clamping  it  loosely  in  the  tool  post  and  over  but  not 
touching  the  work.  If  the  cutting  edge  is  not  parallel  with  the 
work,  rap  the  tool  until  it  appears  to  be  so.  Feed  the  tool 
down  with  the  hand  crank  until  it  just  touches  the  work.  Now 
move  the  ram  of  the  shaper  forward  by  pulling  the  belt  by 
hand.  The  fine  chip  or  dust  removed  by  the  tool  will  show  if 
it  is  set  in  the  proper  position. 

Direction  of  Feed. — If  the  tool  appears  to  cut  deepest  at 
the  center,  it  may  be  fed  in  either  direction,  Fig.  19,  but  if  it  is 
set  so  that  one  side  cuts  slightly  deeper  than  the  other,  as  in 
Fig.  20,  the  direction  of  the  feed  should  be  as  indicated  by  the 
arrow.  Feeding  in  the  opposite  direction  is  apt  to  make  the 
tool  chatter  because  of  the  wide  cutting  edge  that  is  in  contact 
with  the  work. 

The  curve  of  the  cutting  edge  in  Fig.  19  and  the  angle  at 


TESTING  FOR  SQUARENESS 


23 


which  the  tool  is  set  in  Fig.  20  are  greatly  exaggerated  The 
cutting  edge  should  be  straight  within  .002"  or  .003"  and  one 
side  should  not  be  set  more  than  .002"  or  .003"  deeper  than 

the  other. 

Depth  of  Finishing  Cut— 
The  finishing  tool  is  intend- 
ed for  shallow  cuts  of  not 
more  than  .01"  and  works 
better  if  still  less  is  taken. 
In  general  practice  it  is  cus- 
FIG.  19  FIG.  20  tomary  to  plane  to  the  finish 

line    with    a    roughing    tool 

and  use  the  finishing  tool  merely  to  remove  the  marks  of  the 
roughing  tool.  If  .02"  or  .03"  are  to  be  removed  several  cuts 
should  be  taken. 

Rate  of  Feed. — As  the  finishing  tool  has  a  wide  cutting 
edge  a  coarse  feed  may  be  used.  In  this  case  about  1/8"  per 
stroke  will  do.  With  most  shapers  this  is  about  equivalent  to 
one-half  turn  of  the  hand  crank.  The  feeding  should  be  done  by 
hand  and  care  taken  to  note  the  position  of  the  crank  after 
each  turn.  This  insures  a  uniform  rate  of  feed. 

Cutting  Speed. — The  cutting  speed  should  be  determined 
by  experience.  In  most  cases,  however,  40  to  50  strokes  per 
minute  will  give  good  results  for  both  the  finishing  and  rough- 
ing cuts. 

Testing  the  Work  for  Squareness. — After  roughing  and  fin- 
ishing cuts  have  been  taken,  the  work  is  removed  from  the 
vise  and  tested  with  a  square  to  make  sure  the  surface  being 
machined  is  square  with  A  and  parallel  with  B.  The  work 
must  be  tested,  because  the  solid  jaw  of  the  vise  cannot  be 
depended  on  as  being  square  or  the  base  upon  which  B  rests 
as  being  parallel  to  the  travel  of  the  tool. 

A  pair  of  calipers  is  used  to  determine  if  the  sides  D  and  B 
are  parallel. 

Resetting  Work. — In   case   D   is   not   square   with  A   the 


24 


SHAPER  WORK 


setting  in  the  vise  may  be  corrected,  within  certain  limits,  by 
having  the  metal  strip  H,  Fig.  16,  higher  or  lower.  When  this 
strip  is  near  the  top  of  the  vise  the  block  will  be  very  slightly 
tipped  so  that  the  edge  2  will  be  a  little  higher  than  1.  With 
H  at  or  close  to  the  bottom  the  effect  will  be  just  the  opposite 
and  a  little  more  metal  can  be  cut  off  at  edge  1  than  at  2. 

If  the  two  sides  B  and  D  are  not  parallel  additional  pieces 
of  paper  may  be  placed  under  the  thickest  end. 

It  may  be  necessary  to  take  several  trial  cuts  before  the 
block  is  properly  set  in  the  vise.  These  cuts  should  be  taken 
with  the  finishing  tool  since  it  is  quickly  fed  across  the  work 
and  does  not  remove  much  metal. 

The  work  is  now  machined  to  the  finished  size.  If  it  is 
necessary  to  remove  more  than  1/32"  of  metal,  time  will  be 
saved  by  first  using  the  roughing  tool,  as  the  finishing  tool  is 
not  intended  to  take  more  than  .01"  per  cut. 


FIG.  21 


Planing  the  End. — To  plane  the  end  of  the  block  it  is  held 
in  the  vise  in  the  same  manner  as  when  planing  side  D.  It  is 
first  set  approximately  straight  by  using  the  square  as  in 
Fig.  21.  In  this  view  the  solid  jaw  of  the  vise  is  not  shown. 

The  base  of  the  vise  cannot  be  relied  upon  to  be  parallel 
with  the  travel  of  the  tool,  so  that  a  trial  roughing  and  finish- 


PLANING  THE  END  25 

ing  cut  should  be  taken  to  test  the  squareness  of  the  surface  E 
with  the  sides  B  and  D. 

In  order  to  test  side  E  with  B  and  D  it  will  be  necessary 
to  slide  the  blade  of  the  square  thru  the  head  so  that  it  may 
be  used  as  a  try-square.  In  this  case  the  testing  may  be  done 
without  removing  the  work  from  the  vise. 

If  the  block  is  not  set  square  it  may  be  tilted  a  little  in  the 
vise  by  holding  the  grain  end  of  a  piece  of  wood  against  one 
corner  and  rapping  the  wood  with  a  hammer.  Most  machin- 
ists, however,  prefer  the  following  method :  If  it  is  desired  to 
plane  off  a  little  more  at  1  than  at  2,  Fig.  21,  rap  down  on  the 
end  2  with  the  face  of  a  hammer ;  this  will  cause  it  to  settle  a 
little  deeper  in  the  vise  or  the  end  1  to  rise. 

By  placing  the  fingers  on  the  side  of  the  block  so  that  they 
are  in  contact  with  the  work  and  vise  at  the  time  it  is  being 
rapped  one  can  determine  to  some  extent  by  the  feeling  the 
amount  the  work  is  being  moved. 

Care  should  be  taken  when  rapping  not  to  mar  the  surface 
so  deep  that  the  marks  will  show  after  the  work  is  finished. 

Another  trial  cut  should  now  be  taken  and  the  process 
repeated  if  it  is  not  square. 

To  Prevent  Corners  from  Breaking. — It  will  be  noticed 
that  both  the  finishing  and  roughing  tools  break  off  the  corner 
of  the  work  at  the  outer  end  of  the  cut.  To  prevent  this  the 
corner  is  filed  off  at  an  angle  of  about  20°  with  the  surface 
being  planed,  and  as  deep  or  slightly  deeper  than  the  finishing 
cut  is  to  be. 

On  work  of  this  size  the  corner  should  be  filed  off  when  the 
surface  has  been  planed  to  within  1/32"  or  1/16"  of  the  fin- 
ished size.  The  important  thing  is  to  be  sure  to  file  off  the 
corner  before  it  breaks  out  deeper  than  the  finished  size. 

After  this  end  is  finished  reverse  in  vise  and  plane  end  F  to 
the  size  given  in  the  drawing. 


26 


SHAPER  WORK 


Problem  3.— Planing  One  Surface  Parallel  With  Another  and 
Planing  Angles. 


1    1        A-  :     z" 

[_ 

°  i-' 

i    . 

h-  -  -21= H 


FIG.  22 


Sequence  of  Operations: 

1.  Lay  off  on  one  end  of  block  the  outline  of  the  finished 
piece. 

2.  Clamp  in  vise,  Fig.  23. 

3.  Plane  side  C  to  size  with  roughing  and  finishing  tools. 

4.  Rough  out  the  angles  with  a  roughing  tool,  Figs.  24 
and  25. 

5.  Finish  the  angles. 

C 


B 


FIG.  23 

In  laying  off  the  outline  of  the  finished  piece  the  combina- 
tion square  can  be  used  for  the  measurements  and  to  mark  the 
90°  angle.  A  thread  gauge  or  a  bevel  protractor  is  used  for 
the  60°  angle. 

Clamping  in  Vise. — The  work  is  clamped  in  the  vise  as 
shownjn  Fig.  23.  The  parallels  J  and  K  are  longer  than  the 


ROUGHING  OUT  ANGLES 


27 


work  and  high  enough  so  that  the  jaws  of  the  vise  grip  on 
about  1/2"  of  the  work.  The  object  in  clamping  on  only  a 
small  area  of  the  sides  is  to  make  it  easier  to  rap  the  work 
down  on  the  parallels. 

Clamp  the  work  tight,  and  rap  the  top  with  a  hammer  to 
force  it  down  tight  on  the  parallels. 

Care  should  be  taken  before  clamping  the  work  that  the 
movable  jaw  is  tight  on  the  base.  If  it  is  loose  it  will  be 
impossible  to  rap  the  work  down  solid  on  the  parallels. 


FIG.  24 

Planing  One  Side  Parallel  with  Another. — After  taking  a 
roughing  and  finishing  cut,  caliper  the  block  at  each  corner  to 
see  if  it  is  uniform  in  thickness.  If  one  corner  is  thicker  than 
another,  place  one  or  more  pieces  of  paper  under  that  corner 
and  take  another  trial  cut.  This  operation  is  repeated  until  the 
sides  A  and  C  are  parallel.  Then  finish  side  C  to  size. 

Roughing  Out  the  Angles. — The  angles  are  roughed  out 


28  SHAPER  WORK 

with  the  regular  roughing  tool,  cutting  as  close  to  the  lines  as 
possible.  These  roughing  cuts  should  be  heavy  so  as  to 
remove  the  metal  quickly.  The  tool  should  be  started  at  the 
outside  and  fed  toward  the  center.  If  the  automatic  feed  is 
used  it  should  be  disengaged  when  the  tool  is  within  about 
1/16"  of  the  finish  line,  and  the  feed  continued  by  hand.  Wher 
roughing  out  the  angles,  set  the  head,  clapper  box  and  tool  as 
in  Figs.  24  and  25. 

Setting  the  Head,  Clapper  Box,  and  Tool.— For  the  90° 
angle  loosen  the  clamping  screvv  N,  Fig.  24,  and  move  the 
clapper  box  to  about  the  angle  shown.  The  side  of  the  tool 
should  be  nearly  vertical,  as  at  0. 


— R 


FIG.  25 

Setting  the  clapper  box  at  this  angle  causes  the  tool  to 
swing  away  from  the  vertical  side  of  the  work  on  the  return 
stroke  of  the  shaper.  If  it  were  set  at  the  opposite  angle  it 
would  swing  into  the  work. 

For  the  60°  angle  set  the  head  to  an  angle  of  30°  with  the 
vertical,  using  the  graduations  on  the  quadrant  of  the  head  R, 
Fig.  25.  Move  the  clapper  box  to  about  the  angle  shown.  It 


FINISHING  THE  <5o°  ANGLE  29 

should  be  noticed  that  the  angle  at  which  this  is  set  is  just  the 
opposite  of  the  one  used  when  cutting  the  90°  angle.  This  is 
because  the  tool  is  to  cut  on  the  opposite  side. 

Finishing  the  60°  Angle. — The  tool  for  finishing  the  angle 
is  ground  a  little  less  than  60°,  and  with  cutting  edges  on  the 
side  and  bottom  L  and  M,  Fig.  26. 

First  adjust  it  so  that  the  bottom  is  nearly  parallel  with  the 
top  of  the  block  as  at  I  in  Fig.  27,  being  sure  that  the  point  is 
slightly  deeper,  say,  about  .001",  than  the  rest  of  the  tool.  To 
prove  that  this  is  so,  pull  the  belt  by  hand  with  the  tool  just 
touching  the  work.  The  deepest  part  of  the  tool  will  remove  a 
small  chip  or  some  dust. 

Move  the  tool  to  the  side  of  the  angle  at  G  and  feed  it 
down  with  the  hand  crank  to  remove  the  round  corner  left  by 
the  roughing  tool.  Finish  the  bottom  by  feeding  the  tool  from 
the  outer  edge  into  the  corner.  The  point  of  the  tool  being  set 
deeper  insures  the  full  depth  of  the  cut  to  the  sharp  corner. 


FIG.  26  FIG.  27  FIG.  28 

Start  a  cut  from  the  top  of  the  60°  angle  and  feed  down  to 
the  bottom.  Now  adjust  the  tool  so  that  it  is  nearly  parallel 
to  the  side  as  at  H  in  Fig.  28,  being  sure  that  the  point  cuts 
the  deepest.  Take  a  finishing  cut,  beginning  at  the  top  and 
feeding  down  until  the  point  just  touches  the  bottom. 

This  tool,  like  practically  all  finishing  tools,  should  be  kept 
sharp  by  grinding  and  oilstoning.  It  should  not  be  used  for 
cuts  of  more  than  .01"  in  depth. 

Finishing  the  Right  Angle. — When  the  60°  angle  has  been 
finished,  the  90°  angle  is  finished  in  about  the  same  manner. 
The  head  must  be  returned  to  its  vertical  position  and  the 


30  SHAPER  WORK 

clapper  box  tilted  as  in  Fig.  24.    The  tool  used  is  ground  a 
little  less  than  90°,  Fig.  29. 

The  bottom,  or  base  of  the  angles,  S  and  T,  Fig.  29,  should 
be  finished  to  the  same  level.  To  do  this  the  tool  is  set  so  that 
it  just  touches  the  surface  T.  The  final  finishing  cut  is  then 
taken  on  S  without  changing  the  height  of  the  tool. 


FIG.  29  FIG.  30 

Filing  the  Angles. — After  the  angles  are  machined  they 
may  be  finished  smoother  with  a  file.  A  10"  smooth  square 
file  with  a  safe  edge  may  be  used  for  the  right  angle  as  at  U, 
Fig.  30,  and  a  10"  smooth  half-round  file  for  the  60°  angle.  The 
latter  should  have  a  safe  edge  at  V  so  it  will  not  cut  into  the 
side  when  filing  the  bottom. 


Questions — Chapters  I  and  II 

1.  Why  do  we  chip  and  file  a  surface  by  hand  instead  of 
using  a  machine? 

2.  What  kind  of  chisels  are  used  for  chipping  a  flat  sur- 
face? 

3.  Why  should  the  outer  surface  of  cast  iron  be  removed 
before  filing? 

4.  Describe  the  different  kinds  of  files  in  common  use. 

5.  Why  should  care  be  exercised  in  grinding  a  scraper? 

6.  Why  are  scrapers  oilstoned? 

7.  Describe  the  principal  parts  of  a  shaper. 

8.  Why  is  high  speed  steel  used  for  a  roughing  tool  and 
carbon  steel  for  a  finishing  tool? 

9.  Should  a  coarse  or  fine  feed  be  used  when  taking  a 
finishing  cut? 

10.  How  deep  a  cut  should  be  taken  when  using  a  finish- 
ing tool  ? 

11.  In  problem  3,  why  is  the  outline  of  the  finished  piece 
laid  out  on  the  end  of  the  block  ? 

12.  What  are  parallels  used  for? 

13.  Why  is  the  clapper  box  set  at  an  angle  when  using  the 
vertical  feed? 

14.  When  planing  the  30°  angle,  why  is  the  head  set  at 
this  angle? 

15.  When  finishing  angles,  how  is  the  tool  set  so  that  it 
will  cut  a  smooth  surface  and  a  sharp  corner? 

31 


CHAPTER  III 
DRILLING 

The  Drill  Press. — The  size  of  a  drill  press  is  determined  by 
the  maximum  diameter  of  the  work  which  can  be  centered 
with  the  spindle.  Hence  on  a  16"  machine  the  distance  from 
the  center  line  of  the  spindle  to  the  column  is  about  8". 

Fig.  31  shows  a  20"  complete  drill  with  back  gears.  It  has 
8  changes  of  speed,  ranging  from  25  to  300  revolutions  per 
minute.  The  back  gears  are  located  at  the  top  of  the  machine 
and  are  shifted  by  means  of  the  lever  shown  directly  beneath 
them.  This  machine  has  both  hand  and  automatic  feeds  and 
is  also  provided  with  an  automatic  stop  for  drilling  a  number 
of  holes  of  the  same  depth. 

When  work  is  clamped  to  the  table  of  the  machine,  it  may 
be  moved  to  any  desired  position  for  drilling  by  rotating  the 
table  and  swinging  the  table  arm  about  the  column.  To  hold 
the  table  in  position  the  wrench  shown  underneath  it  and  a 
similar  one  on  the  column  are  tightened.  The  table  may  be 
raised  or  lowered  by  means  of  the  hand  crank  on  the  column. 

The  drills  used  in  this  machine  generally  range  from  1/4" 
to  1  1/2",  but  larger  or  smaller  ones  may  be  used.  In  most 
shops,  however,  light  high-speed  machines  are  used  for  small 
drills  and  heavier  machines  for  the  larger  sizes. 


32 


FIG.  31 
TWENTY-INCH  COMPLETE  DRILL 


33 


34 


DRILLING 


Problem  4. — Drilling  and   Tapping. 
Piece  A  is  an  unfinished  cast-iron 

plate. 
Piece  B  is  Problem  3. 


6 

C 

I 

\ 

/ 

K 

L 

M 

N 

H 

D 

\ 

J 

FIG.  32 


FIG.  33 


Sequence  of  Operations : 

1.  Grind  the  rough  surfaces  of  piece  A. 

2.  Lay  off  the  centers  for  holes  in  piece  A. 

3.  Drill  1/2"  holes  in  piece  A. 

4.  Place  A  on  B  and  scribe  position  of  holes  on  B. 

5.  Drill  B  with  13/32"  drill  13/16"  deep. 

6.  Tap  holes  in  B  with  1/2"  U.  S.  S.  plug  tap. 

7.  Tap  bottom  of  holes  wth  1/2"  U.  S.  S.  bottom  tap. 

8.  If  screws  bind  in  holes  of  piece  A,  file  with  round  file. 

Grinding  Piece  A. — As  it  comes  from  the  foundry  the  cast- 
iron  piece  A  is  usually  rough.  It  should  be  smoothed  up  on 
the  grinding  wheel  before  laying  out  the  holes. 

Laying  Out  the  Centers  of  the  Holes. — Piece  A  being  a 
rough  and  unfinished  casting,  is  not  apt  to  be  square  or  true  to 
size.  It  is  therefore  advisable  to  first  mark  the  center  lines  CD 
and  EF,  Fig.  33. 

To  clo  this  the  surface  is  first  chalked  to  make  the  lines 
plainly  visible.  Mark  C  and  D  at  the  center  of  the  two  ends 
and  as  close  to  the  ends  as  possible.  Center  punch  them  with 


DRILLING  AND  TAPPING  35 

a  small  center-punch  and  draw  a  line  between  them.  With  a 
pair  of  dividers  and  with  C  and  D  as  centers  describe  the  arcs 
which  locate  E  and  F.  The  line  thru  these  two  points  will 
be  at  right  angles  with  CD  and  at  its  center. 

Next  mark  with  the  dividers  on  each  side  of  CD  half  of  the 
total  distance  between  the  centers  of  holes  and  draw  GH  and 
IJ.  From  EF  mark  off  on  these  lines  the  required  spacing  of 
the  holes  K,  L,  M,  and  N. 

To  prove  that  the  hole  centers  are  laid  out  square,  measure 
the  distance  from  L  to  M  and  from  K  to  N  with  the  dividers. 
Check  the  layout  with  a  rule  to  see  if  the  centers  are  the  cor- 
rect distances  apart. 

When  the  intersections  are  in  the  right  positions  for  the 
hole  centers,  mark  them  with  a  small  center-punch.  Now 
scribe  circles  about  these  points  a  little  larger  than  the  size  of 
the  holes  to  be  drilled  so  that  after  drilling  it  may  be  seen  if 
the  hole  is  in  the  right  position. 

Holding  the  Work — This  problem  being  small  in  compar- 
ison with  the  holes  to  be  drilled,  should  be  clamped  to  the 
table  of  the  drill  press,  Fig.  34,  or  held  in  a  drill  vise,  Fig.  35. 
When  the  former  method  is  used,  the  work  should  be  placed 
so  that  the  drill  is  above  one  of  the  slotted  holes  in  the  table. 
The  object  of  this  is  to  avoid  drilling  into  the  table.  In  using 
the  vise,  the  parallels  should  not  be  directly  under  the  drill. 


Jft. 


FIG.  34  FIG.  35 

If  the  holes  were  small,  say  less  than  1/4",  or  the  casting 
larger,  it  could  be  held  by  hand.  In  this  case  the  work  should 
rest  on  a  piece  of  wood.  Since  the  wood  is  soft  the  work  is 


36 


DRILLING 


less  liable  to  slip  out  of  the  hand  than  when  placed  on  the 
smooth  surface  of  the  drill-press  table.  The  slipping  does  not 
usually  occur  until  the  point  of  the  drill  pierces  thru  at  the 
end  of  the  hole.  Then  it  will  slip  unless  held  firmly. 

Selecting  the  Drill. — Drills  are  usually  designated  by  their 
size  and  the  shape  of  their  shanks.  The  size  refers  to  the 
diameter  of  the  drill.  The  shank  is  the  end  of  the  drill  by 
which  it  is  held  in  the  machine. 

The  common  drill  sizes  as  listed  in  most  catalogs  run  from 
1/16"  to  3",  varying  by  1/64".  The  sizes  usually  found  in 
shops,  however,  run  about  as  follows :  1/16"  to  1/2"  by  1/64", 
1/2"  to  1"  by  1/32",  1"  to  2"  by  1/16". 

Drills  are  also  made  in  number  and  letter  sizes.  The  num- 
ber sizes  run  from  No.  1,  which  is  .2280  in  diameter,  to  No.  80, 
which  is  .0135"  in  diameter.  There  are  80  different  sizes. 
The  letter  drills  range  from  A,  with  a  diameter  of  .234",  to  Z, 
which  is  .413"  in  diameter,  and  are  26  in  number. 

The  shank  of  the  common  drill  is  either  straight  or  tapered. 
When  straight  it  is  held  in  the  machine  with  a  drill  chuck. 
Taper-shank  drills  are  held  in  the  spindle  as  shown  in  Fig. 

36.    The  tongue,  or  tang,  of  the 
3          drill,  A,  fits  into  a  slot  at  the 
end  of  the  taper  hole  in   the 
spindle  and  makes  the  drill  ro- 
tate   with    the    spindle.       The 
tapered  shank  keeps  the  drill 
from  dropping  out.  To  remove 
the   drill   from   the   spindle,   a 
.taper     drift,     B,     is     used     as 
FIG.  36  shown. 

The  advantages  of  the  taper-shank  drill  are  that  it  runs 
true  and  is  more  conveniently  held  in  the  machine  for  large 
sized  holes.  Straight-shank  drills  larger  than  3/4"  must  be 
held  in  a  chuck  so  large  that  it  often  interferes  with  the 
drilling. 


SELECTING  THE  DRILL  37 

In  most  shops  drills  up  to  3/16"  diameter  are  used  with 
straight  shanks  and  those  from  3/16"  to  3/4"  in  diameter  with 
either  straight  or  taper  shanks.  Drills  larger  than  3/4"  in 
diameter  usually  have  taper  shanks. 

Straight-shank  drills  cost  less  than  those  with  taper  shanks 
and  are  therefore  used  whenever  possible. 


FIG.  37 

The  steel  sleeve  or  bushing  shown  in  Fig.  37  is  used  when 
the  shank  of  a  taper-shank  is  smaller  than  the  hole  in  the 
spindle  of  the  machine.  Sometimes  when  using  small  drills 
in  a  large  machine  it  is  necessary  to  use  two  or  three  of  these 
sleeves. 

After  selecting  the  drill,  examine  the  edges.  If  they  are 
dull,  sharpen  them  on  the  grinding  wheel. 

How  the  Drill  Should  Be  Ground. — The  common  twist  drill 
has  two  cutting  edges,  A  and  B,  Fig.  38.  Like  other  tools, 
these  must  be  ground  with  clearance  C  in  order  to  cut  when 
the  drill  is  forced  into  the  metal  and  rotated  as  indicated  by 
the  arrow. 

The  cutting  edges  A  and  B  should  each  make  an  angle  of 
59°  with  the  axis  of  the  drill.  They  should  be  of  equal  length 
in  order  to  bring  the  point  of  the  drill  in  the  center.  If  the 
point  is  off  center,  only  one  edge  of  the  drill  will  cut.  This 
not  only  reduces  its  efficiency,  but  also  produces  a  hole  larger 
than  is  intended. 

There  are  two  methods  of  sharpening  a  drill,  by  machine 
and  by  hand.  In  shops  where  a  great  deal  of  drilling  is  re- 
quired, a  drill  grinding  machine  is  used. 

Hand  Grinding. — When  it  is  necessary  to  sharpen  a  drill 


38 


DRILLING 


by  hand,  and  especially  one  that  is  larger  than  3/8",  a  drill 
grinding  gauge  should  be  used,  Fig.  39. 

The  cutting  edge  on  smaller  drills  may  be  gauged  by  eye. 


FIG.  38 


FIG.  39 


If  the  side  of  the  grinding  wheel  is  used  instead  of  the  periph- 
ery, it  is  easier  to  produce  a  good  cutting  edge. 

Speed  of  Drill. — The  speed  of  the  drill  depends  upon  its 
size,  the  material  being  drilled,  and  the  feed  used. 

The  following  table  will  give  beginners  some  idea  of  the 
range  of  speeds  for  different  sized  drills  made  of  carbon  steel. 


Diameter 

Revolutions  per  minute 

Drill 

Soft  Steel 

Cast  Iron 

Brass 

1/8 

850 

1190 

1770 

1/4 

390 

565 

855 

3/8 

265 

370 

412 

1/2 

200 

260 

370 

3/4 

112 

168 

265 

SPEED  OF  DRILL  39 

Machinists  do  not,  as  a  rule,  consult  a  table  for  drill  speeds 
because  the  hardness  of  the  material  varies,  and  drilling  ma- 
chines are  not  usually  calibrated  for  the  spindle  speeds.  It  will 
therefore  require  some  practical  experience  before  a  beginner 
can  properly  determine  the  speeds  for  different  sizes  of  drills. 

Centering  the  Drill. — There  are  two  common  methods  that 
could  be  used  for  centering  the  drill  in  piece  A.  In  either  case 
the  center-punch  mark  should  be  enlarged  to  about  1/16"  in 
diameter. 

The  first  method  is  to  drill  a  small  hole  about  1/8"  in  diam- 
eter and  3/16"  deep.  This  hole  acts  as  a  guide  for  the  1/2" 
drill  and  insures  its  being  in  the  correct  position. 

In  the  second  method  a  1/2"  drill  is  used  to  make  a  coun- 
tersink in  the  work  about  1/4"  in  diameter.  If  this  counter- 
sink is  not  in  the  center  of  the  circle,  chip  a  small  groove  on 
the  side  that  is  farthest  from  it,  as  in  Fig.  40,  with  a  round- 
nose  chisel  or  center  gouge.  Drill  a  little  deeper  and  if  the 
countersink  still  does  not  center,  repeat  the  operation. 

In  either  method  the  drill  must  be  centered 
before  it  cuts  to  its  full  size. 

Laying  Off  Holes  in  Piece  B. — After  the  holes 
have  been  drilled  in  piece  A,  place  it  in  position 

F '  on  B.     With  a  scriber  lay  out  the  circles  on  B 

by  marking  thru  the  holes  in  A. 

Drilling  Piece  B. — The  holes  in  piece  B  should  be  drilled  a 
little  larger  than  the  diameter  at  the  bottom  of  the  threads  of 
a  1/2"  tap.  This  is  13/32  of  an  inch. 

Center  punch  the  center  of  the  circles  as  accurately  as  pos- 
sible by  eye.  The  drill  should  be  centered  by  the  second 
method  described  above. 

Drilling  a  Fixed  Depth. — The  desired  depth  of  hole  may  be 
obtained  with  the  aid  of  the  graduations  on  the  spindle  of  the 
the  drill  press.  In  case  the  spindle  is  not  calibrated  a  mark 
may  be  made  on  it  with  a  piece  of  chalk  to  indicate  when  the 
desired  depth  has  been  reached. 


CHAPTER  IV 
TAPS  AND  DIES 

Use  of  Taps. — Taps  are  used  to  make  inside  threads ;  they 
may  be  used  by  hand  or  in  a  machine.  They  vary  in  size  to 
correspond  with  the  standard  screws.  Students  who  wish  to 
study  the  different  standards  are  referred  to  any  machinist's 
supply  catalog  which  will  give  a  complete  list  of  all  standard 
screws,  taps,  and  dies. 

Hand  Tapping. — Clamp  the  work  in  the  bench  vise  and 
tap  the  holes,  first  using  a  1/2"  plug  tap,  Fig.  42.  Then  a 
1/2"  bottoming  tap,  Fig.  43. 


FIG.  41 


FIG.  42 


FIG.  43 

The  plug  tap  is  started  by  pressing  down  on  it  and  turning 
it  with  the  tap  wrench  shown  in  Fig.  44.  After  the  tap  has 
entered  deep  enough  to  cut  a  full  thread,  in  this  case  about 
5/16"  deep,  it  is  no  longer  necessary  to  press  down  on  it  as  the 
tap  will  then  draw  into  the  work  when  turned. 

A  tap  will  work  better  if  it  is  turned  backwards  occasion- 
ally, say  1/8  of  a  turn,  instead  of  turning  it  continuously  in  one 

40 


HAND  TAPPING 


41 


direction.  The  tap  wrench  for  this  size  tap  should  be  about  12" 
long. 

Lard  oil  should  be  used  for  a  lubricant  when  tapping  cast 
iron  or  steel.     Brass  is  usually  tapped  dry. 

I 


FIG.  44 

The  accuracy  with  which  a  hole  is  tapped  depends  upon 
the  operator,  as  the  tap  will  not  follow  the  hole.  The  tap 
should  therefore  be  started  square  with  the  face  of  the  work. 
In  some  cases  this  may  be  judged  by  eye,  but  it  is  usually 
necessary  for  beginners  to  use  a  square  or  the  blade  of  a 
square,  as  in  Fig.  45.  In  this  case  the  blade  is  placed  back 
of  the  tap  and  away  from  the  hole.  The 
tap  is  squared  up  by  bringing  its  shank 
parallel  with  the  edge  of  the  blade.  If  the 
blade  were  placed  over  the  edge  of  the 
hole,  the  small  ridge  produced  by  the  tap 
would  tip  it  out  of  square.  The  tap  must 
be  squared  before  it  cuts  to  its  full  di- 
ameter, as  any  attempt  to  straighten  it 
after  that  is  liable  to  break  it. 

As  the  plug  tap  is  tapered  at  the  end, 
it  will  not  cut  the  full  size  of  thread  to 
the  bottom  of  the  hole.  It  is  desirable  on 
account  of  strength  to  have  the  length  of 
the  full  threads  greater  than  the  diameter 

of  the  screw.  The  tapping  should  therefore  be  finished  with 
a  bottoming  tap  which  will  cut  full  threads  nearly  to  the 
bottom  of  the  hole. 

The  reason  for  not  using  the  bottoming  tap  for  the  entire 
tapping  operation  is  that  it  is  practically  impossible  to  start 
such  a  tap. 


\ 


FIG.  45 


42 


TAPS  AND  DIES 


If  the  holes  extended  all  the  way  thru,  the  taper,  tap  Fig. 
41  would  be  preferred  by  some  mechanics  as  it  starts  a  little 
easier  than  the  plug  tap. 

Filing  Holes  in  Piece  A. — In  case  the  holes  in  piece  B  do 
not  match  up  exactly  with  those  in  A,  the  screws  will  bind  or 


'WVWWW 

' 


WWWWVv 


FIG.  46 


will  not  go  in  at  all.     It  is  then  necessary  to  file  the  holes  in 
A  with  a  round  file  until  the  screws  no  longer  bind. 


FIG.  47.    DIES 


MACHINE  TAPPING 


43 


To  conserve  time,  file  only  that  part  of  the  hole  which 
binds  on  the  screw. 

Machine  Tapping. — Work  is  often  tapped  in  the  lathe  as 
In  Fig.  46.  Here  a  hole  is  tapped  in  the  end  of  a  shaft.  The 
tap  is  usually  turned  by  hand  and  as  it  is  drawn  in  the  hole  is 


FIG.  48 

followed  up  with  the  tail-stock  center.     The  center  supports 
the  end  and  insures  true  work. 

To  prevent  the  spindle  of  lathe  from  turning,  lock  it  by 
engaging  back  gears. 


Die 


FIG.  49 


FIG.  50 


Use  of  Dies. — Dies,  Fig.  47,  are  used  to  produce  outside 
threads,  as  in  threading  bolts,  etc.    Like  taps  they  are  made  in 


44 


TAPS  AND  DIES 


sizes  to  correspond  with  standard  screws  and  bolts.  They 
may  be  used  in  a  machine  or  by  hand  very  much  the  same 
as  taps.  In  both  cases  a  lubricant  is  used 

Fig.  49  shows  the  hand  application.  The  die  is  held  in  the 
die  stock,  Fig.  48,  by  a  set  screw.  The  guide  or  bushing  in- 
sures cutting  the  threads  approximately  true. 


FIG.  51 

It  will  be  noticed  that  the  threads  on  one  side  of  the  die 
have  more  taper  than  the  other;  this  is  the  starting  side. 
Where  threads  are  to  be  cut  close  to  a  shoulder,  as  in  Fig.  50, 
it  is  first  threaded  with  the  die  in  the  stock,  as  in  Fig.  49,  using 
a  3/4"  guide  and  1/2"  die;  then  by  reversing  the  die  a  full 
thread  may  be  cut  close  to  the  shoulder.  The  die  stock  for 
this  size  die  should  be  12"  or  14"  long. 

Fig.  51  shows  the  common  method  of  using  the  die  in  the 
lathe.  Work  can  be  threaded  quickly  with  a  die  but  the 


USE  OF  DIES  45 

threads  will  not  be  as  true  as  when  cut  with  a  threading  tool. 
Dies  are  less  liable  to  break  when  used  in  the  lathe  than 
are  taps ;  therefore  they  may  be  used  with  power  or  by  hand. 
When  using  the  power  the  lathe  should  run  slowly. 


CHAPTER  V 
LATHE  WORK 

Descriptor!  of  Lathe. — The  lathe,  Fig.  52,  has  a  constant- 
speed  drive,  and  it  may  be  driven  with  a  belt  running  from  a 
countershaft  or  from  a  line  shaft  to  the  pulley  1,  or  from  a 
motor  mounted  upon  the  headstock.  A  lathe  of  this  type  is 
called  a  selective-head  lathe. 

The  principal  advantages  of  this  kind  of  a  lathe  as  com- 
pared with  one  driven  with  a  cone  pulley  are  that  the  change 
of  speed  is  more  quickly  and  easily  made,  and  it  is  more  pow- 
erful. 

The  driving  pulley  1  is  connected  to  the  live  spindle  by 
change  gears.  To  obtain  the  12  different  spindle  speeds  the 
gears  are  shifted  with  the  levers  2,  3,  4. 

The  spindle  of  this  lathe  is  different  from  most  lathe  spin- 
dles in  that  the  threads  which  receive  the  chuck  or  face-plate 
are  cut  inside  the  flange  or  collar  5,  instead  of  on  the  outside 
of  the  end  or  nose  of  the  spindle.  The  nose  6  fits  a  correspond- 
ing hole  in  the  chuck  or  face  plate  and  is  of  such  length  that 
the  chuck  is  guided  true  when  screwed  on,  thus  eliminating 
the  danger  of  crossing  the  threads. 

The  levers  26,  27,  and  28  control  the  gears  that  are  used 
for  thread  cutting  and  for  the  feed.  This  feature  is  called 
the  quick-change  gears.  The  threads  and  feeds  that  the  lathe 
will  cut  and  the  corresponding  positions  for  the  levers  are  reg- 
istered on  the  index  plate  25.  This  device  is  much  quicker  and 
more  convenient  than  taking  off  and  putting  on  gears  as  is  the 
case  with  the  lathe  shown  in  Fig.  73,  page  60. 

The  levers  29  and  30  are  fastened  to  the  same  shaft  and 
are  used  to  start,  stop,  brake,  and  reverse  the  lathe.  The  rea- 
son there  are  two  levers  for  this  purpose  is  so  that  the  oper- 
ator can  control  the  lathe  while  standing  either  in  front  of  the 
carriage  or  at  the  end  of  the  lathe  when  changing  the  gears, 

46 


4? 


48  LATHE  WORK 

PARTS  OF  LATHE 

The  selective-head  lathe  has  practically  all  the  parts  that 
a  cone-pulley  lathe  has  except  the  back  gears  and  the  cone 
pulley. 

Head-Stock  Group 

1.  Driving  pulley. 

2,  3,  4.     Levers  for  changing  spindle  speeds. 

5.  Flange  of  spindle  threaded  on  the  inside  to  receive  face 
plate  or  chuck. 

6.  Spindle  nose. 

7.  Live  center. 

8.  Lever  for  reversing  lead  screw. 

Tail-Stock  Group 
9.     Tail-stock  center,  also  called  dead  center. 

10.  Tail-stock  spindle. 

11.  Lever  for  clamping  tail-stock  spindle. 

12.  13.     Bolts  for  clamping  tail-stock  to  bed. 

14.  Hand  wheel  for  adjusting  tail-stock  center. 

15.  Adjusting  screw  which  together  with  one  on  the  op- 
posite side  controls  the  alignment  of  dead  center  with  live 
center. 

Carriage  Group 

16.  Tool  post. 

17.  Compound  rest. 

18.  Cross-slide  hand  crank. 

19.  Carriage  hand  wheel. 

20.  Longitudinal-feed  clutch  knob. 

21.  Cross-feed  clutch  knob. 

22.  Lever  which  controls  direction  of  feed.     This  lever 
should  always  be  in  the  center  or  neutral  position  when  cut- 
ting threads. 

23.  Lever  for  connecting  carriage  with  lead  screws  when 
cutting  threads.     This  should  never  be  thrown  in  if  the  feed 
lever  22  is  in  the  top  or  bottom  hole. 


PARTS  OF  LATHE  49 

24.  Graduated  dial.    By  its  use  there  is  no  need  of  revers- 
ing the  lathe  when  cutting  threads. 

Other  Parts 

25.  Index  plate. 

26.  27,  28.     Levers  which  control  change  gears  for  thread 
cutting  and  feed. 

29,  30.     Levers  for  starting,  stopping,  and  reversing  lathe. 

31.  Lead-screw. 

32.  Ways  upon  which  the  carriage  travels. 

33.  Lathe  bed. 

34.  Lathe  legs. 

Problem  5.— Fit  Shaft  to  Collar — Running  Fit. 

Machine  Steel 


FIG.  53 

Sequence  of  Operations: 

1.  Cut  off  stock. 

2.  Center  both  ends. 

3.  Place  work  between  lathe  centers. 

4.  Finish  the  ends. 

5.  Turn  shaft  nearly  to  size. 

6.  Finish  to  size  by  filing. 

Cut  off  with  a  power  hack-saw  a  piece  of  steel  6  1/16"  long 
from  a  bar  1"  in  diameter.  This  will  allow  1/16"  for  finishing 
the  ends  and  3/16"  for  turning  the  diameter. 

An  experienced  lathe  operator  would  use  a  piece  of  steel 
7/8"  in  diameter,  but  for  beginners  it  is  better  to  use  larger 
stock  to  allow  for  practice  turning. 

Centering. — Center  both  ends  in  the  centering  machine. 
The  size  of  the  center  in  this  shaft  should  be  from  3/16"  to 
1/4"  in  diameter.  Larger  work  should  have  deeper  centers. 


so 


LATHE  WORK 


If  a  centering  machine  is  not  available,  .the  work  may  be 
centered  by  first  locating  the  center  with  a  .pair  of  dividers 
and  center-punch  and  then  using  a  combination  drill  and 
countersink  in  the  lathe  as  shown  in  Fig.  55.  Or  it  may  be 
centered  in  the  drill  press.  In  both  cases  the  work  is  held  by 
hand  to  prevent  it  from  turning.  As  this  work  is  to  be  turned, 
it  is  necessary  to  center  it  only  approximately  true. 


,-Drin  and  Countersink 


FIG.  55 


Steady  Rest 


FIG.  56 


FIG.  57 


FIG.  58 


Accurate  Centering. — When  the  work  is  to  be  centered 
accurately,  it  may  be  done  by  putting  one  end  in  the  lathe 
chuck  and  the  other  in  a  steady  rest.  A  pointed  tool  is  then 


FIT  SHAFT  TO  COLLAR 


51 


used  in  the  tool  post  as  shown  in  Fig.  56.  The  point  of  this 
tool  has  an  angle  of  60°,  the  same  as  the  lathe  centers,  and  is 
ground  like  a  flat  drill  so  that  it  cuts  on  both  sides. 

After  the  shaft  is  centered  with  this  tool,  a  center-hole 
about  1/8"  in  diameter  should  be  drilled.  This  is  done  by 
holding  the  drill  in  the  tail-stock  of  the  lathe  with  a  drill- 
chuck,  as  shown  in  Fig.  57.  The  object  of  this  center-hole  is 
to  give  the  center  of  the  shaft  a  bearing  on  the  lathe  center  a 
short  distance  back  from  the  point,  as  at  A  in  Fig.  58. 

Placing  Work  in  Lathe. — The  work  is  made  to  rotate  on 
the  lathe  centers  by  fastening  a  lathe  dog  to  the  shaft  at  the 
head-stock  end,  as  shown  in  Fig.  59. 

Head   Stock  tail   Stock 


FIG.  59 

There  are  a  number  of  different  sized  dogs;  the  smallest 
size  that  will  go  over  the  shaft  should  be  used. 

The  tail-stock  center  is  adjusted  so  that  the  shaft  will 
rotate  freely,  yet  be  tight  enough  to  allow  no  slack,  or  lost 
motion.  Since  the  shaft  rotates  on  this  center,  it  should  be 
kept  well  lubricated  by  using  machine  oil,  or  a  mixture  of 
graphite  and  oil. 

To  get  the  best  results  in  turning  this  sort  of  work,  it  is 
necessary  to  face  both  ends  before  turning  and  to  rough-turn 
the  whole  piece  to  within  about  0.03"  or  0.04"  of  the  finished 
size  before  any  part  of  it  is  finished.  However,  it  is  not  always 
necessary  to  do  this.  The  object  of  first  rough-turning  the 
shaft  all  o\^cr  is  to  remove  the  internal  strains  of  the  steel  and 
to  wear  the  centers  down  to  a  good  bearing  before  any  finish- 


52 


LATHE  WORK 


ing  cuts  are  taken.  The  purpose  of  facing  the  ends  is  to  get 
them  square,  or  true,  and  smooth,  and  the  shaft  the  proper 
length. 

Finishing  End  of  Shaft. — To  face  the  ends,  use  a  regular 
turning  tool,  starting  to  cut  from  the  outside  and  feeding  by 
hand  towards  the  center  with  the  cross  feed.  Such  a  tool  will 
leave  a  ridge  near  the  center,  as  shown  in  Fig.  60.  This  ridge 
is  cut  off  with  a  sharp  pointed,  side-cutting  tool,  as  shown  in 


FIG.  60 


FIG.  61 


Fig.  61,  which  is  also  used  for  taking  the  finishing  cut  across 
the  whole  end  of  the  bar.  When  taking  this  finishing  cut, 
lard  oil,  or  some  other  lubricant,  should  be  used.  (See  use  of 
lubricant,  page  57.) 

After  the  finishing  cut  has  been  taken,  any  small  ridge,  or 
fin  that  remains  at  the  edge  of  the  center  is  removed  by  slightly 
changing  the  angle  of  the  tool  in  the  tool  post  and  allowing 
about  1/64"  play  between  the  centers.  Having  the  work  loose 
like  this  when  the  lathe  is  running,  allows  the  extreme  point 
of  the  side  tool  to  extend  beyond  the  edge  of  the  center  and 
cut  a  smooth  end. 

If  the  stock  is  cut  off  fairly  true  and  close  to  size,  it  will  not 
be  necessary  to  use  the  round-nose  tool  shown  in  Fig.  60. 

The  lathe  should  run  slowly  for  the  finishing  cut  and  fast 
when  the  regular  turning  tool  is  used. 

Turning  the  Shaft. — The  first,  or  roughing  cut,  is  taken 
with  a  high-speed  steel  tool,  or  bit,  fastened  in  a  tool  holder. 


FINISHING  END  OF  SHAFT 


53 


The  tool  holder  is  clamped  in  the  tool  post  of  the  lathe  so  that 
the  point  of  the  tool  is  at,  or  a  little  above,  the  center,  or  axis, 
of  the  lathe,  as  Fig.  62. 

If  the  point  of  the  bit  is  too  high,  it  is  easy  to  see  that,  as 
the  shaft  rotates,  the  tool  will  not  cut  at  all,  Fig.  63.  In  case 
the  tool  is  set  below  the  center,  the  cutting  action  is  very 
poor,  therefore  turning  tools  are  never  set  as  in  Fig.  64. 


FIG.  62 


FIG.  63 


FIG.  64 


FIG.  65 

Speed  of  the  Lathe. — In  taking  the  heavy  roughing  cuts, 
the  belt  may  be  placed  on  the  second  largest  step  of  the  cone, 
while  for  the  finishing  cuts  the  lathe  should  run  a  little  faster, 
say  with  the  belt  in  the  next  smaller  step. 

Grinding  Turning  Tool. — The  front,  or  point,  and  the  sides 
of  the  tool  are  ground  at  an  angle,  which  is  called  the  clear- 
ance. If  the  tool  has  too  little  clearance,  it  will  not  cut  freely, 
while  if  it  has  too  much  clearance,  the  point  will  be  so  thin 
that  it  will  break  off  or  become  dull  quickly. 

The  top  of  the  tool  is  also  ground  at  an  angle.  This  is 
called  the  rake.  If  the  tool  has  too  little  rake,  it  will  not  cut 


54  LATHE  WORK 

freely  and  if  it  has  too  much,  the  edge  will  soon  break  down. 

It  requires  some  practice  for  a  beginner  to  learn  the  proper 
rake  and  clearance  that  should  be  given  to  a  tool,  Fig.  65 
shows  a  tool  ground  with  clearance  and  rake  that  will  give 
very  good  results. 

Direction  Tool  Should  Travel. — The  depth  of  the  first  cut 
should  be  about  1/16"  and  the  travel  of  the  tool  should 
be  from  the  tail-stock  end  towards  the  head-stock.  If  the 
travel  is  in  the  opposite  direction,  the  pressure  on  the  tail- 
stock  center  is  increased,  causing  it  to  heat  quickly. 

The  length  of  the  cut  should  be  as  great  as  possible  with- 
out the  lathe  dog  striking  the  tool,  or  cross-rest. 

Adjusting  the  Lathe  to  Turn  Straight. — After  the  first  cut 
the  work  should  be  calipered,  and  if  it  is  being  turned  taper- 
ing, the  tail-stock  should  be  adjusted  so  that  the  lathe  will  turn 
straight. 

The  tail-stock  adjustment  is  made  by  loosening  the  main 
clamping  nut  B  and  one  of  the  screws  C  and  then  tightening 
the  other  screw  C  on  the  opposite  side  of  the  tail-stock,  Fig.  59. 

If  the  shaft  is  larger  at  the  tail-stock  end,  the  tail-stock 
should  be  moved  towards  the  front  of  the  lathe  one-half  the 
difference  between  the  diameters  of  the  shaft  at  the  two  ends. 

In  doing  close  work,  the  tail-stock  should  be  adjusted  as 
closely  as  possible,  but  in  this  case  if  it  is  off-center  only  a 
little,  say  0.002"  or  0.003",  it  will  be  close  enough  providing  it 
is  set  so  that  the  shaft  will  be  turned  larger  at  the  head-stock 
end.  If  the  tail-stock  is  set  so  that  the  shaft  is  turned  larger 
at  the  tail-stock  end,  the  shaft  will  be  too  small  at  the  other 
end  after  the  finishing  cut  is  taken. 

Fitting  Shaft  to  the  Collar. — After  the  roughing  cut  is  taken 
and  the  lathe  has  been  adjusted  so  that  it  turns  approximately 
straight,  the  end  of  the  shaft  is  turned  for  about  1/4"  so  that 
it  will  just  fit  the  hole  in  the  collar,  shown  in  the  drawing  of 
Problem  5.  To  measure  this:  first  set  the  inside  calipers  to 
the  diameter  of  the  hole  in  the  collar,  then  set  the  outside 


ADJUSTING  THE  LATHE  55 

calipers  to  the  inside  calipers  and  caliper  the  shaft  as  accur- 
ately as  possible.  For  a  final  test  of  this  diameter,  remove 
the  work  from  the  lathe  and  try  it  with  the  collar  itself. 

The  advantage  of  turning  but  1/4"  at  the  end  of  the  shaft 
is  this :  if  the  finishing  cut  were  set  too  deep,  only  1/4"  of  the 
shaft  would  be  too  small,  while  if  this  cut  were  taken  the 
whole  length,  the  entire  shaft  would  be  too  small. 

After  the  shaft  has  been  turned  at  the  end  so  that  it  fits  the 
collar,  the  rest  of  the  shaft  should  be  turned  a  little  larger,  say 
0.002"  or  0.003"  in  diameter.  This  will  leave  enough  to  finish 
with  a  file. 

Finishing  Cut. — The  tool  used  for  the  roughing  cut  may 
also  be  used  for  finishing,  but  it  is  usually  necessary  to  re- 
sharpen  it.  After  it  is  reset  in  the  tool  post,  the  point  should 
be  flattened  a  little  wider  than  the  pitch  of  the  feed,  say  about 
1/32",  and  parallel  with  the  work.  This  is  done  with  an 
oilstone. 

Filing. — The  object  of  filing  is  to  take  out  the  tool  marks, 
but  it  is  also  found  to  be  much  easier  to  make  a  close  fit  by 
filing  off  the  last  0.002"  or  0.003"  than  to  take  so  small  a  cut 
with  a  tool.  The  amount  of  allowance  for  filing  depends  upon 
the  character  of  the  finishing  cut.  Since  the  less  filing  re- 
quired the  better,  the  finishing  cut  should  be  made  as  smooth 
as  possible. 

For  filing  work  on  a  lathe,  a  single-cut  file  is  used.  This  is 
called  a  lathe,  or  mill  file. 

The  stroke  of  the  file  should  be  slow,  steady,  and  straight 
across  the  shaft.  The  lathe  should  run  a  little  faster  for  filing 
than  for  turning,  the  object  being  to  have  the  work  make  sev- 
eral revolutions  for  a  single  stroke  of  the  file.  If  the  lathe  runs 
too  slowly  and  the  stroke  of  the  file  is  too  fast,  the  shaft,  in- 
stead of  being  filed  round,  will  have  a  series  of  flat  places  on 
the  surface. 

After  the  work  is  finished  as  close  to  the  dog  as  possible, 
reverse  it  in  the  lathe  and  finish  that  part  where  the  dog  was 
fastened. 


56  LATHE  WORK 

Problem  6. — Turning  and  Threading  a  Taper  Shaft. 


FIG.  66 

Sequence  of  Operations: 

1.  Lay  off  the  dimensions  1  3/4",  3",  1  1/4". 

2.  Turn  the  large  end  as  shown  in  Fig.  68. 

3.  Turn  the  small  end  and  the  taper. 

4.  Cut  threads  and  polish  threads  and  taper. 

5.  Cut  threads  on  large  end. 

The  finished  shaft  in  Problem  5  may  be  used  for  Prob- 
lem 6. 

Place  the  shaft  in  the  bench  vise  and  with  a  rule  snd  scriber 
lay  off  the  dimensions:  1  3/4",  3",  and  1  1/4".  Then  center- 
punch  the  lines  just  deep  enough  so  that  they  can  be  easily 
seen  when  the  work  is  in  the  lathe,  or  enlarge  them  with  the 
corner  of  a  file. 

Turn  the  large  end  first. 

When  it  is  necessary  to  turn  a  fixed  distance,  or  to  a  line 
as  in  this  case,  it  is  well  to  disconnect  the  feed  when  the  tool 
is  within  about  1/8"  from  the  end  of  the  cut  and  to  feed  the 
tool  the  rest  of  the  distance  by  hand.  If  this  is  not  done,  the 
tool  may  travel  farther  than  it  is  intended  to. 

It  is  better  to  turn  the  portions  to  be  threaded  a  little  under 
rather  than  over  size.  For  if  they  are  over  size,  the  threads 
will  not  fit  the  standard  size  nut,  but  if  under  size  the  threads 
do  not  need  to  be  cut  so  deep  in  order  to  fit  the  nut. 

For  measuring  the  diameters  of  this  piece  set  the  calipers 
as  accurately  as  possible  by  measuring  from  the  end  of  the 
rule,  as  shown  in  Fig.  67. 


TURNING  A  TAPER  SHAFT 


57 


Use  of  Lubricant. — A  lubricant  is  a  liquid  used  in  pro- 
ducing a  smooth  finish  when  cutting  steel  and  in  some  cases 
other  metals.  It  is  also  used  to  prevent  tools  overheating 
when  doing  heavy  duty. 

Lard  oil  is  generally  considered  the  best  lubricant,  but 
owing  to  the  high  cost  its  use  has  been  greatly  reduced  by 
substituting  such  compounds  as  soap  water,  soda  and  water, 
etc. 

In  making  this  problem  a  lubricant  should  be  used  on  the 
following  operations:  cutting  recess,  chamfering  and  thread 
cutting. 


FIG.  67 


FIG  68 


Cutting  Recess. — The  surface  at  the  end  as  well  as  the 
recesses  between  the  threads  and  the  taper  are  cut  with  a 
square-nose,  or  cutting-off  tool,  Fig.  68. 

This  tool  should  have  a  sharp  smooth  edge,  the  point  being 
set  level  with  the  center  of  the  lathe. 

After  the  end  is  turned  to  size,  reverse  the  work  in  the 
lathe  and  turn  the  other  end  and  the  taper  before  cutting  the 
threads. 

Turning  Taper. — The  drawing  calls  for  a  taper  of  1"  per 
foot.  This  is  cut  by  using  a  taper  attachment,  or  by  setting 
the  tail  stock  off-center.  As  most  lathes  are  not  provided  with 


58 


LATHE  WORK 


a  taper  attachment,  the  latter  method  will  be  used. 

If  the  work  were  12"  long,  the  tail-stock  would  be  moved 
off-center  1/2"  to  turn  a  taper  of  1"  per  foot.  It  being  only 
6"  long,  the  tail-stock  is  set  off-center  but  half  that  amount, 
or  1/4". 

Before  taking  the  finishing  cut,  caliper  both  ends  to  prove 
that  the  lathe  is  cutting  the  correct  taper. 

Size  and  Shape  of  Threads. — The  threads  are  cut  to  fit 
1/2"  and  5/8"  nuts  having  United  States  Standard  threads. 
These  threads  are  flattened  at  the  top  and  bottom  to  the 
amount  of  1/8  of  the  pitch  instead  of  being  sharp  pointed  as 
in  the  case  of  Standard  V-threads. 


FIG.  69 


FIG.  70 


FIG   7J 


Pitch. — The  pitch  of  the  thread  is  the  distance  from  the 
center  of  one  thread  to  the  center  of  the  one  adjoining.  On 
the  end  of  the  problem  having  13  threads  per  inch  the  pitch 
is  1/13",  so  that  the  width  of  the  flat  at  the  top  and  bottom  of 
this  thread  should  be  1/8  of  1/13",  or  about  .009". 

Lead. — The  lead  of  the  thread  is  the  distance  a  nut  on  the 
screw  will  travel  in  making  one  complete  turn.  For  single 
threads  the  pitch  and  lead  are  the  same,  but  for  double  threads 
the  lead  is  twice  the  pitch. 


SIZE  AND  SHAPE  OF  THREADS  59 

Grinding  Tool. — The  sides  of  U.  S.  S.  threads  form  an  angle 
of  60°.  To  cut  this  thread  in  a  lathe,  a  tool  the  same  shape  as 
the  threads  is  used.  A  gauge  for  grinding  this  tool  accurately 
is  shown  in  Fig.  69. 

If  a  U.  S.  S.  thread  gauge  is  not  available,  the  tool  can  be 
ground  with  the  aid  of  a  regular  thread  and  center  gauge, 
shown  in  Fig.  70.  With  such  a  gauge  the  angle  can  be  ground 
accurately,  but  it  will  be  necessary  to  measure  the  flat  point 
with  a  rule. 

Where  the  thread  to  be  cut  is  as  fine  as  13  per  inch  the  flat 

surface  at  the  point  of  the  tool 
is  so  small  that  the  extreme 
point  can  be  oil-stoned  off  in- 
stead of  being  taken  off  with 
the  grinding  wheel.  The  flat 
point  should  never  be  wider 
than  the  standard  size,  but  if 
it  is  a  little  too  narrow  it  will 
make  very  little  difference  in 
ordinary  lathe  work. 

The  top  of  the  tool  A,  Fig.  72,  should  be  ground  so  that  it 
will  be  approximately  in  a  horizontal  plane  when  set  in  the 
lathe. 

Setting  Tool. — To  set  the  tool  so  that  both  sides  of  the 
thread  will  have  the  same  angle,  the  thread  gauge  is  used  as 
shown  in  Fig.  71.  The  tool  should  be  set  on  a  level  with  the 
center  of  the  lathe. 

How  Lathe  is  Geared.— To  cut  13  threads  per  inch  the 
work  must  make  13  revolutions  while  the  carriage,  which  car- 
ries the  tool,  travels  one  inch.  For  this  purpose  the  lathe  spin- 
dle is  connected  to  the  lead  screw  with  the  proper  size  gears 
and  the  lead  screw  to  the  carriage  by  a  split  nut.  This  split 
nut  is  back  of  the  carriage  apron  and  is  opened  and  closed  by 
the  lever  E,  Fig.  73. 

If  the  lead  screw  of  the  lathe  has  6  threads  per  inch,  the 


60 


LATHE  WORK 


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HO W  THE  LATHE  IS  GEARED  61 

gearing  to  cut  13  threads  per  inch  must  have  the  same  ratio 
as  6  is  to  13.  To  cut  16  threads  the  ratio  would  be  6  to  16. 

It  is  not  necessary  to  figure  the  size  of  gears  for  the  dif- 
ferent threads  as  all  lathes  are  provided  with  an  index  plate 
that  designates  the  proper  size  gears  to  be  placed  on  the  stud 
B  and  screw  C,  Fig.  73,  for  the  desired  thread. 

To  Set  Change  Gear. — To  change  these  gears,  first  loosen 
the  nuts  holding  the  stud  and  screw  gears  B  and  C.  Next 
loosen  the  nut  G.  This  will  allow  the  intermediate  gear  to 
drop  away  from  the  stud  gear  B.  Then  loosen  the  nut  H  so 
that  the  intermediate  gear  can  be  drawn  back  away  from  the 
gear  on  the  lead  screw  C.  The  gears  may  now  be  changed. 

When  the  gears  are  put  in  mesh,  they  should  be  set  so 
that  there  will  be  a  little  slack,  or  lost  motion,  between  the 
different  gears.  If  they  are  set  too  close  together,  they  will 
make  a  great  deal  of  noise  when  running  and  there  is  also 
danger  of  breaking  the  teeth. 

While  all  lathes  are  not  designed  alike  the  method  of 
changing  the  gears  is  very  much  the  same  on  all  machines 
except  those  having  the  quick  change-gear  device.  With  a 
lathe  having  such  a  device,  instead  of  changing  the  gears  on 
the  stud  and  screw  the  same  result  is  obtained  by  shifting  a 
combination  of  levers. 

Why  Feed  Should  Be  Disconnected. — The  mechanism  that 
controls  the  feed,  or  travel,  of  the  tool  when  cutting  threads  is 
independent  of  that  used  for  the  feed  when  doing  plain  turning. 
The  two  feeds  usually  run  at  different  speeds  so  that  if  they 
are  both  in  action  at  the  same  time  the  gears  in  the  carriage 
will  break.  For  this  reason  all  lathes  are  provided  with  some 
means  of  disconnecting  the  feed  used  for  plain  turning  when 
cutting  threads. 

To  disconnect  the  feed  on  the  lathe  shown  in  Fig.  73, 
move  the  lever  J  to  the  central,  or  neutral,  position.  This 
should  always  be  done  before  starting  to  cut  the  threads. 

Speed  of  Lathe. — The  lathe  should  run  slower  for  cutting 


62 


LATHE  WORK 


threads  than  for  plain  turning.  With  most  lathes  if  the  belt 
is  on  the  largest  step  of  the  cone  it  will  give  about  the  right 
speed  for  cutting  the  threads  in  this  problem. 

The  object  of  running  the  lathe  slowly  is  to  give  the  op- 
erator time  to  draw  back  the  tool  at  the  end  of  the  cut  and  to 
obtain  a  smoother  cut.  If  the  speed  of  the  lathe  is  too  fast, 
the  cutting  action  will  be  so  quick  that  the  tool,  instead  of 
cutting  clean  and  smooth  will  tear  out  the  metal,  leaving  a 
rough  surface. 

The  .slower  the  lathe  runs  the  easier  it  is  to  cut  the  threads, 
but  it  will  also  take  longer  to  do  the  job.  It  therefore  re- 
quires practical  experience  to  determine  the  proper  speed  to 
be  used  for  cutting  the  different  size  threads. 

Chamfering. — After  the  lathe  and  tool  are  properly  set, 
chamfer  off  the  sharp  corners  where  the  threads  begin  and 
end  with  the  side  of  the  thread  tool.  The  depth  of  this  cut 
should  be  about  the  same  as  that  of  the  threads  when  finished. 


If  the  corners  are  not  chamfered,  the  threads,  when  cut,  will 
form  a  very  thin  edge,  or  fin,  at  the  ends. 

Use  of  Adjustable  Stop. — To  regulate  the  depth  of  each  cut 


CHAMFERING  63 

an  adjustable  stop  is  used  as  shown  at  K,  Fig.  74.  First  move 
the  tool  so  that  the  point  just  touches  the  work,  then  adjust  the 
screw  on  the  attachment  K  so  that  the  cross-rest  will  not  go 
in  any  farther.  Now  move  the  carriage  by  hand  until  the  point 
of  the  tool  is  a  little  past  the  tail-stock  end  of  the  work; 
close  the  split  nut  on  the  lead  screw  with  the  lever  E,  Fig  73 ; 
and  turn  the  screw  on  the  attachment  K  so  that  the  tool  can  be 
moved  in  just  enough  to  take  a  very  light  cut. 

Start  the  lathe  and  when  the  tool  has  reached  the  end  of 
the  cut  back  it  out  and  reverse  the  lathe.  By  reversing  the 
lathe  the  tool  is  returned  to  the  starting  point  without  dis- 
connecting any  of  the  gearing.  The  object  of  drawing  the 
tool  back  is  to  prevent  it  from  dragging  on  the  work  during 
its  return. 

The  tool  will  never  travel  over  the  same  path  on  the 
reverse  as  on  the  forward  movement  of  the  lathe  on  account 
of  the  slack,  or  lost  motion,  in  the  gears. 

This  first  cut  is  taken  to  prove  that  the  lathe  is  properly 
geared,  so  the  work  should  be  measured  with  a  rule,  or  screw 
pitch  gauge,  or  compared  with  a  standard  tap. 

Adjust  the  screw  at  K  until  the  tool  can  be  moved  in 
deeper  for  the  next  cut  and  repeat  the  operation  until  the 
thread  is  nearly  finished.  Then  the  tool  should  be  reset  so 
that  it  will  cut  on  only  one  side  at  a  time. 

If  the  lathe  has  no  adjustable  stop  the  depth  of  cut  can 
be  regulated  by  the  graduations  on  the  crossfeed  shaft  near 
the  hand  crank. 

Finishing  Side  of  Thread. — When  roughing  out  the  threads, 
the  tool  cuts  on  both  sides  of  the  point  since  it  is  fed  straight 
into  the  work.  It  is  much  easier,  though,  to  finish  the  threads 
smooth  if  the  tool  cuts  on  one  side  only.  If  the  lathe  has 
no  compound  rest  this  is  done  by  rapping  the  end  of  the 
tool  holder  so  that  it  is  turned  in  the  tool  post  just  enough  to 
change  the  position  of  the  point  of  the  tool  about  .01"  or  .02". 

To  prove  that  the  tool  is  set  over  the  proper  amount,  turn 


64  LATHE  WORK 

the  lathe  forward  by  hand  a  few  revolutions,  to  take  out  all 
the  slack,  or  lost,  motion  in  the  gears,  then  move  the  tool  into 
the  groove  of  the  thread  until  one  side  just  touches  the  side 
of  the  thread.  The  other  side  of  the  tool  should  then  be 
about  .01"  or  .02"  away  from  the  side  of  the  thread. 

After  the  tool  is  properly  adjusted,  set  the  stop  K.  The 
tool  is  then  drawn  back  and  the  lathe  reversed  until  the  tool 
is  at  the  end  of  the  work  ready  for  a  cut.  It  usually  requires 
several  finishing  cuts  to  take  out  all  the  rough  marks  left  by 
the  roughing  cuts. 

When  this  side  of  the  thread  is  finished,  the  other  side  is 
finished  in  the  same  manner. 

Use  of  Compound  Rest. — If  the  lathe  is  provided  with  a 
compound  rest,  a  somewhat  different  procedure  is  usually 
followed,  since  the  rest  can  be  set  at  an  angle  of  30°  with 
the  work,  as  in  Fig.  74. 

In  this  case  the  tool  is  moved  in  by  turning  the  small 
handcrank  M  until  the  side  at  O  has  been  cut  to  the  proper 
depth.  While  making  these  first  cuts,  the  stop  K  is  merely 
used  to  bring  the  cross-rest  to  the  same  position  each  time. 
The  tool  is  then  drawn  back  slightly  with  the  hand-crank  M 
and  the  stop  K  adjusted  so  that  the  tool  can  be  moved  straight 
in  by  means  of  the  hand-crank  O.  This  will  finish  the  other 
side  of  the  thread  at  P. 

To  determine  when  the  thread  is  cut  to  the  proper  size  the 
work  is  removed  from  the  lathe  and  tested  with  a  standard 
nut  having  U.  S.  S.  threads. 

It  should  be  remembered  that  in  order  to  cut  a  smooth 
thread  the  tool  must  be  kept  sharp  and  the  work  must  be  wet 
with  a  lubricant. 

After  the  threads  are  cut  on  this  end  of  the  problem,  it 
is  reversed  in  the  lathe  and  the  other  end  threaded  in  a  similar 
manner. 

To  prevent  the  screw  of  the  dog  from  marring  the  portion 
already  threaded,  two  nuts  should  be  screwed  on  and  the  dog 
fastened  to  the  nuts. 


USE  OF  COMPOUND  REST 


65 


How  to  Reset  the  Tool. — When  cutting  threads  of  this  size 
and  larger,  the  tool  usually  becomes  dull  from  taking  the 
heavy  roughing  cuts.  It  is  then  necessary  to  resharpen  it 
before  taking  the  fine  finishing  cuts. 

To  reset  the  tool  in  the  lathe  first  get  the  angles  correct, 
as  shown  in  Fig.  71.  Then  revolve  the  lathe  forward  by  hand 
to  take  up  slack  in  the  gears  and  move  the  tool  in  close  to 
the  threads.  If  the  tool  is  in  a  position  so  that  it  will  cut  too 
much  off  one  side  of  the  thread,  it  may  be  changed  by  disen- 
gaging the  reversing  gears  with  lever  R,  Fig.  73,  and  turning 
the  lathe  by  hand.  When  the  tool  is  in  the  proper  position 
relative  to  the  groove  of  the  thread,  the  reverse  gear  lever  R 
is  reset. 

In  a  case  where  the  tool  is  off  the  desired  position  only  a 
very  little,  it  may  be  corrected  by  the  rapping  process. 

If  the  lathe  has  a  compound  rest  the  tool  may  be  brought 
to  the  correct  position  by  turning  the  hand-crank  M,  Fig.  74. 

It  would  be  well  for  beginners  to  practice  thread  cutting 
on  a  piece  of  scrap  steel  before  trying  to  cut  them  on  the 
problem. 

Polishing. — The  taper  may  be  polished  with  fine  emery 
cloth  and  oil  and  the  threads  with  the  end  of  a  soft  piece  of 
wood.  The  work  should  rotate  at  the  highest  speed  possible, 
and  loose  on  the  lathe  centers. 

Problem   7.— Boring  and  Turning   Cast   Iron—Finished   All 
Over. 


/-Knurl 


FIG.  75 


66 


LATHE  WORK 


Sequence  of  Operations: 

1.  Finish  the  inside  of  Piece  A. 

2.  Drill  and  ream  the  hole  in  Piece  B. 

3.  Mount  B  on  mandrel  and  finish  outside. 

4.  Screw  A  on  B  and  finish  the  outside  of  A. 


Piece  A. 

10  Thrds  per  i"    U.S.5. 


T 


— 24- 

FIG.  76.     ROUGH   CASTING 


FIG.  77.    FINISHED  CASTING 


Use  of  Lathe  Chucks. — To  machine  the  inside  of  piece  A 
it  will  be  necessary  to  hold  it  in  a  lathe  chuck.  There  are  two 
kinds  of  lathe  chucks  in  common  use,  the  scroll  or  universal 
three-jaw  chuck  and  the  independent  four-jaw  chuck. 

The  scroll  chuck  is  self-centering,  that  is,  the  three  jaws 
move  to  and  from  the  center  in  unison.  This  chuck  is  used 
principally  for  holding  finished  bars  of  brass,  steel,  and  other 
pieces  when  light  cuts  are  to  be  taken.  It  is  not  suitable  for 
holding  rough  and  irregular  pieces  for  heavy  cuts  as  such 
work  will  spring  the  jaws  and  cause  them  to  be  out  of  true. 

The  independent  four-jaw  chuck  is  not  self-centering,  but 
is  made  heavy  and  strong;  therefore,  it  is  used  for  work  that 
is  not  suitable  for  the  scroll  chuck. 

As  piece  A  is  a  rough  casting  and  heavy  cuts  are  to  be 


CAST  IRON  FINISHED  ALL  OVER 


67 


taken,   the   independent   four-jaw   chuck   should  be   used  for 
holding  it,  Fig.  78. 

Work  of  this  kind  is  usually  chucked  so  that  the  outside 


FIG.  78 

surfaces  will  be  within  1/32"  of  running  true. 

The  process  of  chucking  the  work  is  as  follows: 

Centering  Work  in  the  Chuck. — Place  the  work  in  the 
chuck  and  adjust  the  jaws  until  they  are  all  at  approximately 
equal  distances  from  the  circles  on  the  face  of  the  chuck. 
Then  put  a  cutting-off  tool  loosely  in  the  tool  post  and  move 
it  close  to  the  work  and  as  near  as  possible  to  the  end  of 
the  chuck  jaws.  Revolve  the  lathe  by  hand  to  prove  if  the 
work  is  centered.  If  it  is  not  centered  to  within  1/32",  read- 
just the  jaws  until  it  is.  Now  move  the  cutting-oft  tool  to 
the  end  of  the  work  and  turn  the  lathe  by  hand.  If  the  end 
runs  out  of  true,  rap  it  with  a  hammer  at  such  points  as  will 
correct  its  position. 

Advantage  of  Proper  Chucking. — Fig.  78  shows  the  work 
held  by  the  middle  step  of  the  cone.  One  reason  for  holding 
it  in  this  way  is  to  permit  the  rough  turning  of  the  larger 
step  while  in  the  chuck.  If  the  work  were  held  by  the  small 
end,  it  would  be  apt  to  work  loose  when  taking  the  heavy 
roughing  cuts,  on  account  of  the  distance  that  the  work  pro- 
jects out  and  the  small  diameter  on  which  the  chuck  grips 
compared  with  that  of  the  large  end  which  is  to  be  turned. 

Rough    Turning. — After    the    work    has    been    properly 


68  LATHE  WORK 

chucked,  rough-turn  the  end  and  the  largest  diameter  to 
within  1/32"  of  the  finished  size. 

All  cast  iron  has  a  hard  surface,  or  scale,  from  1/64"  to 
1/32"  deep,  so  that  it  is  necessary  to  run  the  lathe  slower 
for  the  first  cut  than  for  those  made  after  the  scale  has  been 
removed.  In  taking  this  first  cut  the  tool  should  be  set  deep 
enough  to  permit  the  point  to  cut  under  the  scale. 

Speed  of  Lathe. — The  speed  of  the  lathe  in  taking  the 
roughing  cut  on  work  of  this  size  should  be  about  right  if  the 
belt  is  on  the  smallest  step  of  the  cone  and  the  back  gears  arc 
used.  After  the  scale  is  removed,  the  lathe  may  be  run  faster. 
•  A  beginner  will  require  experience  before  being  able  to 
determine  the  proper  speeds  and  feeds  for  the  different  kinds  of 
lathe  work. 

Advantage  of  Roughing  Inside. — As  the  inside  of  piece  A 
must  fit  the  outside  of  the  piece  B,  the  1  1/8"  hole,  the 
threads  and  the  taper  must  be  machined  true  with  each  other, 
or  else  A  will  not  fit  into  B  properly.  Now  if  the  taper  should 
be  finished  and  the  work  moved  in  the  chuck  before  the 
threads  and  the  1  1/8"  hole  are  finished,  they  would  not  be  true 
with  each  other.  For  this  reason  it  would  be  well  to  rough- 
bore  the  inside  to  within  1/32"  of  the  finished  size  before  any 
of  these  three  parts  are  finished. 

Roughing  Inside. — To  rough-bore  the  taper  use  a  regular 
turning1  tool.  Set  the  compound  rest  to  the  correct  angle  and 
feed  the  tool  in  at  that  angle. 

If  the  lathe  is  not  provided  with  a  compound  rest,  the 
taper  may  be  rough-bored  by  turning  both  feeds  by  hand 
and  following  the  cored  surface  as  closely  as  possible. 

The  cored  hole  in  the  rough  casting,  Fig.  76  is  15/16"  in 
diameter  which  allows  3/16"  for  finishing  the  1  1/8"  hole  and 
5/16"  for  the  portion  where  the  threads  are  to  be  cut. 

Use  of  Flat  Drill.— To  rough-bore  the  hole  a  1  1/16"  flat, 
or  lathe,  drill  is  used  as  shown  in  Fig.  78.  The  holder  A  is 
clamped  in  the  tool  post  so  that  the  slot  in  it  will  hold  the 


ROUGHING  INSIDE  69 

drill  at  the  center  of  the  lathe.  If  the  drill  is  held  above  or 
below  the  center,  the  hole  will  be  drilled  larger  than  the 
drill.  To  prove  that  the  slot  in  the  holder  is  at  the  center, 
move  it  close  to  the  tail-stock  center.  After  the  holder  is 
properly  set,  move  it  as  close  to  the  work  as  possible  and 
feed  the  drill  into  the  work  by  turning  the  hand  crank  on  the 
tail-stock. 

If  the  cored  hole  is  out  of  center,  which  is  usually  the 
case,  the  drill  may  wobble  in  the  holder,  thus  drilling  the  hole 
off-center.  To  overcome  this  apply  a  wrench  to  the  drill  and 
hold  it  with  the  hand  in  such  a  way  that  the  corners  of  the 
drill  will  cramp  or  bind  in  the  slot  of  the  holder.  If  the 
cross-slide  of  the  lathe  moves  in  and  out  when  starting  the 
drill,  tighten  the  gib. 

This  drill  removes  the  hard  surface,  or  scale,  and  also 
trues  up,  or  centers,  the  hole  to  within  1/64"  or  1/32".  Now 
enlarge  the  portion  of  the  hole  where  the  threads  are  to  be 
cut  with  a  1  3/16"  drill. 

To  determine  when  this  drill  has  been  fed  in  far  enough, 
mark  on  the  drill  with  a  piece  of  chalk  the  distance  from  the 
end  of  the  work  to  the  point  where  the  recess  is  to  be  cut.  By 
sighting  across  the  end  of  the  work  the  operator  can  then  see 
when  the  drill  has  been  fed  in  the  proper  distance. 

If  a  lathe  drill  is  not  available,  a  twist  drill  may  be  used, 
as  in  Fig.  86,  page  75. 

The  advantage  of  the  lathe  drill  is  that  it  is  cheaper  and 
will  center  the  cored  hole  better. 

The  hole  may  also  be  roughed  out  with  a  boring  bar, 
although  this  will  be  a  somewhat  slower  process. 

Use  of  Boring  Bar. — To  cut  the  square  shoulder  where  the 
threads  begin  and  the  recess  where  they  end,  use  a  tool  and 
boring  bar,  as  shown  in  Fig.  80,  held  in  the  tool  post.  The 
width  of  this  tool  is  5/32",  so  that  it  will  be  necessary  to 
take  two  cuts  to  make  the  recess  wide  enough.  Such  a 
narrow  tool  is  used  because  it  is  less  liable  to  chatter. 


70 


LATHE  WORK 


This  tool  is  ground  with  clearance  at  the  sides  as  well  as 
at  the  front,  and  it  should  also  be  noticed  that  it  is  wider  at 
the  cutting  edge  than  back  close  to  the  boring  bar.     This  is 
done  so  that  when  the  tool  is  fed  into  the  wrork 
there  will  be  little  or  no  chance  of  its  binding 
on  the  side. 

To  obtain  the  correct  setting  for  the  tool, 
move  the  boring  bar  into  the  hole  and  bring 
it  up  close  to  one  side.  The  tool  should  then 
be  adjusted  until  its  cutting  edge  is  parallel 
to  this  surface.  It  can  also  be  set  by  com- 
paring the  side  of  the  tool  with  the  end  of  the 
work. 

The  recess  and  square  shoulder  may  be 
finished  smooth  if  the  finishing  cuts  are  very 
light,  say  .001"  deep. 

To  measure  the  diameter  of  the  recess  use  a  pair  of  inside 
spring  calipers,  Fig.  79. 


FIG.  79 


u 


FIG. 


The  work  is  now  all  roughed  out  so  that  it  makes  very 
little  difference  which  of  the  three  fitting  parts  is  finished  first. 


USE  OF  BORING  BAR 


71 


Finishing  Inside. — The  1  1/8"  hole  has  been  drilled  with  a 
1  1/16"  lathe  drill,  but  as  such  a  tool  cannot  be  relied  upon 
to  drill  true  to  center,  or  size,  it  is  necessary  to  turn  it  out 
with  a  boring  tool.  With  this  tool  the  hole  can  be  bored 
true  to  center  and  within  .01"  o(  the  finished  size. 

The  boring  bar  used  in  this  case  is  the  same  as  shown  in 
Fig.  80,  but  the  cutter  has  a  rounded  point  and  is  similar  to 
the  tool  used  for  outside  turning  except  that  it  is  ground  with 
less  clearance. 

Setting  Boring  Bar. — After  clamping  boring  bar  in  the 
tool  post,  move  it  through  the  hole  to  make  sure  that  it 
clears.  If  the  bar  should  touch  the  hole  it  will  cause  the 
cutter  to  spring  away  from  the  work. 

Why  Reamers  Are  Used. — To  bore  a  hole  straight  and 
true  to  size  requires  considerable  time  and  skill,  therefore,  to 
conserve  time  and  insure  accuracy  the  hole  is  finished  with  a 
shell  or  lathe  reamer  held  in  the  lathe  as  shown  in  Fig.  81 
or  Fig.  82. 


FIG.  81 

Boring  and  Reaming  the  Hole. — Before  starting  the  reamer, 
the  hole  should  be  bored  at  the  end,  for  a  distance  of  about 
1/8",  to  the  size  which  will  just  permit  the  reamer  to  enter. 
This  diameter  must  be  calipered  very  carefully  and  should 
be  tested  with  the  reamer  itself.  The  rest  of  the  hole  is  then 
bored  about  .01"  smaller  in  diameter  to  allow  enough  ma- 
terial for  finishing  with  the  reamer.  This  will  require  several 
cuts  and  the  hole  should  be  calipered  at  both  ends.  Since 


72 


LATHE  WORK 


the  reamer  used  in  this  case  cuts  on  the  sides  as  well  as  on 
the  end,  the  hole  must  be  bored  true  to  center  in  order  to 
be  reamed  true. 

If  the  reamer  has  a  tapered  shank,  it  is  held  in  the  lathe 
by  a  square-shank  socket  and  wrench,  as  shown  in  Fig.  81, 
and  is  fed  into  the  work  by  turning  the  hand-crank  on  the 
tail-stock. 

To  place  the  socket  in  the  lathe  it  will  be  necessary  to 
remove  the  tail-stock  center.  This  is  done  by  turning  the 
hand-crank  until  the  tail-stock  spindle  is  drawn  in  far  enough 
to  force  the  center  out. 

If  a  square-shank  socket  is  not  available  the  reamer  may 
be  mounted  directly  in  the  spindle;  in  this  case  a  dog  should 
be  used  to  prevent  the  reamer  from  turning.  If,  for  any 
reason,  a  dog  cannot  be  used,  one  thickness  of  a  piece  of 
paper  should  be  wrapped  around  the  taper  shank  of  the 
reamer ;  then  in  case  it  should  turn  there  would  be  no  danger 
of  scoring  the  tapered  hole  in  the  tail-stock  spindle. 

In  case  the  reamer  has  a  straight  shank,  it  is  held  as  shown 
in  Fig.  82.  Here  a  dog  is  fastened  to  the  end  of  the  reamer 
and  prevented  from  turning  by  a  tool  clamped  at  an  angle 


FIG.  82 

in  the  tool-post.  The  end  of  the  tool  presses  against  the  dog 
near  the  shank  of  the  reamer  so  that  as  the  reamer  is  fed 
into  the  work  the  carriage  of  the  lathe  is  forced  along  with 
it.  This  causes  the  tool  to  hold  the  end  of  the  reamer  against 
the  center  of  the  tail-stock. 


BORING  AND  REAMING  THE  HOLE  73 

When  reaming  work  in  a  lathe,  if  the  tail-stock  is  off 
center  the  hole  will  be  reamed  too  large  at  the  front  end. 

Accurate  Boring  With  Boring  Bar. — In  turning  out  holes 
with  a  boring  bar,  if  all  the  cuts  are  started  from  one  end, 
that  end  will  be  bored  larger  than  the  other.  In  case  the 
hole  is  to  be  reamed,  the  reamer  will  correct  this,  but  if  the 
hole  is  to  be  finished  with  the  boring  bar  it  will  be  necessary 
to  bore  the  hole  from  both  ends.  This  is  done  by  reversing 
the  feed  of  the  carriage. 

Speed  of  Lathe. — The  speed  of  the  lathe  for  reaming  should 
be  slower  than  when  using  the  boring  bar.  If  the  belt  is  on 
the  second  smallest  step  of  the  cone  with  the  back  gears  in, 
the  lathe  should  have  about  the  right  speed  for  reaming. 
When  using  the  boring  bar,  the  belt  should  be  on  the  largest 
step  of  the  cone  without  the  back  gear. 

Inside  Threading. — The  inside  threads  are  cut  in  very 
much  the  same  manner  as  the  outside  ones.  The  cutting  tool 
is  held  in  the  boring  bar  and,  like  all  boring  tools,  is  ground 
with  less  clearance  than  tools  used  for  outside  work. 

To  regulate  the  depth  of  each  cut,  the  screw  in  the  adjust- 
able stop  is  placed  between  the  stop  and  the  cross-rest.  Then 
by  turning  the  screw  in  after  a  cut  has  been  taken  the  cross- 
rest  can  be  drawn  back  to  permit  a  deeper  cut  with  the  tool. 

Cause  of  Threads  Breaking. — When  cutting  threads  in  cast 
iron,  they  will  break  if  the  roughing  cuts  are  too  heavy  and 
are  liable  to  if  they  are  cut  to  a  sharp  point.  Another  cause 
for  the  breaking  of  cast  iron  threads  is  the  use  of  a  dull  tool, 
or  one  with  too  little  clearance. 

Finishing  Threads. — As  a  general  rule  cast  iron  is  machined 
without  using  a  lubricant,  but  in  finishing  threads  a  little 
lard  oil  will  aid  in  producing  a  smooth  finish. 

Finishing  Ends. — The  end  of  the  work  may  be  finished  by 
taking  a  very  light  cut  with  the  turning  tool  and  then  scraping 
it  with  a  lathe  scraper,  as  shown  in  Fig.  83.  To  provide  a  rest 


74 


LATHE  WORK 


for  the  scraper  a  tool  is  clamped  in  the  tool-post  and  as  close 
as  possible  to  the  surface  being  scraped. 

A  scraper  is  usually  made  from  an  old  file  ground  smooth 
on  the  two  sides  and  with  a  little  clearance  at  the  end. 

Finishing  Taper. — To  finish  the  taper,  set  the  compound 
rest  at  an  angle  of  30°  with  the  axis  of  the  lathe.  Such  a 
rest  is  normally  at  right  angles  with  the  lathe  axis,  so  that 
it  must  be  turned  thru  60°  to  cut  30°  angle.  A  regular 
turning  tool  may  be  used  to  finish  this  angle,  but  it  should 
be  set  so  that  the  straight  side  will  be  nearly  parallel  with 
the  tapered  surface. 


FIG.  83 


FIG.  84 


If  the  lathe  is  not  provided  with  a  compound  rest,  the 
angle  may  be  cut  with  the  side  of  a  tool  set  at  the  proper 
angle.  To  set  this  tool,  use  the  thread  and  center  gage,  as 
shown  in  Fig.  84. 

In  case  the  angle  is  other  than  30°  or  60°,  it  is  neces- 
sary to  set  the  tool  with  a  bevel  and  bevel  protractor. 

After  the  taper  has  been  cut,  it  may  be  finished  smooth  by 
scraping  with  a  lathe  scraper  in  very  much  the  same  manner 
as  shown  in  Fig.  83.  The  tool  that  is  used  as  a  rest  is  set  in 
as  close  as  possible  to  the  taper.  If  this  rest  is  too  far  away 


FINISHING  TAPER 


75 


from  the  surface  being  finished,  the  scraper  will  chatter,  leav- 
ing a  rough  surface. 

Polishing  the  Inside. — Wet  the  inside  with  oil  and  sprinkle 
it  with  a  little  powdered  emery  or  carborundum.  Run  the 
lathe  at  its  highest  speed  and  polish  by  holding  the  end  of  a 
small  piece  of  soft  wood  on  the  work. 

Piece  B. 


10  Thrds  per  1"  U.S  S 


"T 


ROUGH  CASTING 


FIG.  85 


_1 


FINISHED  CASTING 


Drilling  and  Reaming. — This  piece  is  first  placed  in  the 
chuck,  as  shown  in  Fig.  86,  and  the  end  rough-turned  to  see 
if  it  is  a  good  casting.  The  hole  is  then  drilled  with  a  23/32" 


twist  drill  and  reamed  out  to  size  with  a  3/4"  rose  reamer. 

Centering  Twist  Drill. — This  drill  will  not  bore  a  hole  in 
the  center  unless  the  point  is  controlled  in  some  way.  To  do 
this,  a  cutting-off  tool  is  clamped  in  the  tool-post  with  its 
point  well  above  the  center  of  the  lathe  and  is  then  moved 


76  LATHE  WORK 

close  to  the  point  of  the  drill.  As  the  drill  starts  to  cut,  it 
wabbles  a  little  on  account  of  the  point  being  off-center.  The 
cutting-off  tool  is  then  gradually  brought  against  the  drill 
which  is  at  the  same  time  being  slowly  fed  into  the  work  by 
turning  the  hand  crank  on  the  tail-stock.  It  is  necessary  to 
have  the  drill  centered  true  before  it  begins  to  cut  the  full 
diameter. 

The  drill  should  be  placed  in  the  tail-stock  so  that  the 
cutting  edges  are  vertical.  If  they  are  horizontal,  it  will  be 
difficult  to  make  the  drill  center. 

If  the  hole  in  this  piece  were  larger,  it  would  be  cast  with 
a  core  and  then  machined  in  the  same  manner  as  the  1  1/8" 
hole  in  piece  A,  but  since  it  is  cast  solid,  the  hole  can  be 
machined  more  advantageously  by  using  a  twist  drill  and 
a  rose  reamer. 

Reaming. — After  the  hole  has  been  drilled  with  the  23/32 
drill,  bore  it  out  with  a  small  boring  tool  for  about  1/8"  from 
the  end  to  the  diameter  that  will  just  fit  over  the  reamer 
and  insure  its  starting  true.  Ream  the  hole  with  the  reamer 
held  in  the  same  manner  as  the  twist  drill  in  Fig.  86. 

Speed  of  Lathe. — The  lathe  should  run  slower  for  reaming 
than  for  drilling.  The  speed  will  be  about  right  for  this  size 
reamer  if  the  belt  is  on  the  largest  step  of  the  cone  without  the 
back  gears  being  used.  The  speed  for  the  drill  may  be  much 
faster.  With  a  high-speed  steel  drill,  the  belt  can  be  run  on 
the  second  smallest  step  of  the  cone.  If  the  drill  is  made  of 
carbon  steel,  a  slower  speed  should  be  used. 

Advantage  of  Rose  Reamer. — In  drilling  long  holes  like 
this  the  drill  is  very  apt  to  get  off  center  a  little  as  it  is  fed 
deeper  into  the  work,  even  though  it  may  have  been  started 
dead  true. 

The  reamer  used  in  this  case  is  called  a  rose  reamer,  or 
rose  bit,  and  cuts  on  the  end  only,  A,  Fig.  87,  the  rest  of  the 
reamer  acts  as  a  guide.  For  this  reason,  if  the  hole  is  ap- 
proximately true,  say  within  1/64",  it  will  ream  the  hole 


ADVANTAGE  OF  ROSE  REAMER 


77 


straight  and  true  to  size  if  it  is  once  started  true.    It  will  cut 
smoother  and  closer  to  size  if  oil  is  used. 


FIG.  87 

The  shell  reamer  shown  in  Fig.  81  has  a  cutting  edge  on 
the  side  as  well  as  on  the  end,  for  this  reason  it  will  ream  a 
hole  smooth  without  the  use  of  oil.  If  oil  is  used  with  this 
reamer  when  cutting  cast  iron  it  causes  the  cutting  edges  to 
dull  quickly,  thus  reducing  the  diameter. 

Oil  is  used  w^ith  all  kinds  of  reamers  when  cutting  steel. 
Finishing  Corner. — After  the  hole  is  bored  and  reamed,  the 
work  may  be  finished  at  the  end  by  using  a  tool  ground  like 
a  threading  tool,  but  having  an  angle  at  the  point  a  little  less 
than  90°,  as  in  Fig.  88. 

The  boss,  or  hub,  which  is  1  3/8"  in 
diameter,  is  finished  with  one  cutting 
edge  of  this  tool  set  nearly  parallel  to 
the  work,  the  point  being  a  trifle  deep- 
er than  the  rest.  This  will  insure  the 
full  depth  of  cut  for  the  entire  length 
and  also  a  good  sharp  corner.  .The 
direction  of  feed  for  this  tool  should 
be  from  the  end  and  towards  the  square 
corner  or  shoulder.  If  it  is  fed  in  the 
opposite  direction,  the  tool  is  apt  to 
chatter. 

This  tool  is  also  used  to  finish  the  end,  but  it  is  turned  a 
little  in  the  tool-post  so  that  the  other  cutting  edge  is  nearly 
parallel  to  the  surface  to  be  cut.  After  using  this  tool,  the 
work  may  be  finished  smoother  by  scraping  the  ends,  as  in 
Fig.  83,  and  by  filing  the  boss  or  hub. 

Use  of  Mandrel,  or  Arbor. — Before  this  piece  can  be  fin- 


FIG. 


78 


LATHE  WORK 


ished  on  the  outside,  it  must  be  forced  on  a  mandrel  or  arbor, 
and  placed  in  the  lathe,  as  shown  in  Fig  89.  Most  commercial 
shops  are  provided  with .  hardened  steel  mandrels  for  this 
purpose,  but  if  one  is  not  available  it  can  be  made  from  soft 
steel  in  the  following  manner: 


FIG. 


Making  Mandrel. — Cut  off  a  piece  of  steel  of  suitable 
length,  say  6  inches,  and  rough  turn  it  to  within  1/32"  of 
the  diameter  of  the  hole.  Then  turn  it  at  the  end  for  a  dis- 
tance of  about  1/8"  to  the  size  that  will  just  fit  the  hole.  The 
rest  of  the  distance  is  now  turned  .002"  or  .003"  larger  and 
filed  for  about  3"  until  it  will  just  fit  the  hole.  The  next  2" 
are  filed  with  a  slight  taper  so  that  when  the  mandrel  is 
pressed  into  the  hole  it  will  fit  tight  enough  to  hold  the 
casting  while  it  is  being  turned.  This  kind  of  a  fit  is  called 
a  forced,  or  driving  fit. 

When  making  such  a  mandrel,  it  is  not  necessary  to  turn 
that  portion  to  which  the  dog  is  fastened. 

Mounting  Work  on  MandreL — Before  pressing  the  mandrel 
in,  it  should  be  oiled  to  prevent  it  from  being  marred  or 
scored.  Mandrels  are  usually  forced  in  with  a  mandrel  press, 
but  if  one  is  not  available,  they  may  be  driven  in  with  a  ham- 
mer. When  this  method  is  used,  a  piece  of  lead,  or  some 
other  soft  material,  must  be  held  on  the  end  of  the  mandrel 
to  keep  the  hammer  from  marring  the  center. 

Finishing  Outside  of  Piece  B  to  Fit  A. — This  casting  is 
rough-turned  to  within  1/32"  of  the  finished  size  before  any 
part  of  it  is  finished.  The  1  1/8"  end  is  then  turned  until  it 
fits  the  corresponding  part  of  the  hole  in  piece  A  as  closely 


MAKING  MANDREL  79 

?s  possible,  niid  yet  not  so  tight  that  it  cannot  be  freely 
rotated.  This  kind  of  a  fit  is  called  a  close  running  fit. 

Cutting  Threads. — The  portion  to  be  threaded  should  be 
turned  a  little  smaller  than  the  diameter  at  the  bottom  of  the 
threads  in  piece  A.  This  size  is  measured  by  means  of  the 
inside  spring-thread  calipers. 

There  is  no  recess,  or  groove,  cut  at  the  end  of  this  thread, 
so  that  if  the  threading  tool  is  allowed  to  travel  farther  than 
the  end  of  the  preceding  cut,  either  the  point  of  the  tool  or 
the  threads  may  break.  To  prevent  this,  the  lathe  is  stopped 
when  the  tool  is  within  a  half  a  thread  of  the  end  and  the 
cut  finished  by  turning  the  lathe  by  hand.  In  this  way  the 
lathe  is  kept  under  control  and  the  tool  may  be  drawn  back 
when  it  reaches  the  end  of  the  preceding  cut.  Experienced 
lathe  operators  do  not,  as  a  rule,  turn  the  lathe  by  hand,  but 
control  the  lathe  entirely  by  the  shipper. 

The  tool  used  for  cutting  the  thread  should  have  the  point 
at  one  side  of  the  center  as  shown  in  Fig.  71,  page  58;  the 
reason  for  this  is  so  that  it  will  cut  the  thread  close  to  the 
shoulder. 

The  speed  of  the  lathe  for  cutting  this  thread  will  be 
about  right  for  beginners  if  the  belt  is  on  the  second  smallest 
step  of  the  cone  and  the  back  gears  are  thrown  in. 

Finishing  the  Angle,  or  Taper. — The  30°  angle  may  be 
cut  by  setting  the  compound  rest  to  the  correct  angle  and 
using  a  regular  turning  tool.  In  case  the  tool  leaves  a  few 
tool  marks  they  may  be  removed  by  filing. 

If  the  lathe  is  not  provided  with  a  compound  rest,  this 
angle  may  be  cut  by  setting  a  square-nose  tool,  as  in  Fig.  90, 
with  the  aid  of  a  thread  gauge.  Any  other  angle  would  have 
to  be  set  with  a  bevel  and  bevel  protractor. 

This  tool  is  not  as  wide  as  the  surface  to  be  cut  because 
one  that  will  cut  the  full  width  is  very  liable  to  chatter.  It  is 
therefore  better  to  make  several  cuts  with  a  narrow  tool. 
The  surface  can  then  be  finished  smooth  by  filing. 


LATHE  WORK 


The  closeness  of  the  fit  of  this  taper  with  that  in  A  can  be 
tested  by  rubbing  black  paint,  which  consists  of  lamp  black 
and  oil,  on  the  tapered  surface  in  A.  When  B  is  screwed 

into  A,  marks  will  be  made  on  B.  If 
the  error  is  not  too  great  it  may  be 
corrected  by  filing. 

Finishing  Outside  of  Piece  A. — 
Piece  A  may  now  be  screwed  on  B 
and  the  outside  rough-turned  to  within 
1/32"  of  the  finished  size. 

The  ends  of  the  different  steps  are 
finished  to  the  proper  length  with  the 
tool  shown  in  Fig.  88.  This  same  tool 
can  then  be  used  to  turn  the  different 

diameters  to  within  0.002"  or  0.003"  of   the   required  size. 
These  steps  are  brought  to  the  final  size  by  filing. 

Filing. — The  file  for  this  work  should  be  less  than  1"  in 
width.  If  it  is  wider  than  the  steps,  a  beginner  will  usually 
file  the  portion  at  the  end  of  each  step  smaller  in  diameter 
than  that  which  is  close  to  the  square  corners. 


FIG.  90 


FIG.  91 


The  different  diameters  may  be  measured  accurately  with 
the  micrometer  calipers. 

Micrometer  Calipers. — Micrometer  Calipers  are  used  for 
measuring  all  sorts  of  work  where  great  accuracy  is  required. 
The  different  sizes  are  designated  by  the  largest  piece  of  work 


MICROMETER  CALIPERS 


81 


they  will  measure:  i.  e.,  a  1"  micrometer  has  a  range  from  0 
to  1";  a  2"  will  measure  from  1"  to  2",  and  so  on  up  to  12". 
The  12"  size  is  the  largest  usually  listed  by  the  different 
manufacturers,  altho  larger  sizes  can  be  obtained. 

Fig.  91  shows  the  1/2"  size. 

How  to  Read  the  Micrometer. — The  sectional  view  in  Fig 
92  gives  an  idea  of  the  inside  construction  of  the  head  or 
measuring  part  of  the  micrometer. 


FIG.  92 

The  spindle  C  and  the  thimble  D  is  made  in  one  piece. 
The  threads  on  the  spindle  are  40  per  inch,  so  that  by  rotating 
the  thimble  D  40  revolutions  the  spindle  will  move  longitu- 
dinally 1",  and  by  turning  it  one  revolution  the  spindle  will 
move  1/40"  or  .025". 


FIG.  93 

The  thimble  D,  Fig.  93,  has  25  graduations.    If  it  is  ro- 
tated one  graduation  in  the  direction  indicated  by  the  arrow, 


82 


LATHE  WORK 


the  caliper  will  open  at  H  1/25"  of  1/40",  or  .001";  if  it  is 
rotated  6  graduations  it  will  open  .006". 

The  graduation  on  the  sleeve  A,  Fig.  96,  are  .025"  apart, 
and  every  fourth  one  is  numbered.  The  first  numbered  gradu- 
ation represents  .100",  the  second  .200",  and  so  on.  Some 
micrometers  also  have  every  fifth  graduation  numbered ;  in 
this  case  the  numbers  represent  1/8",  2/8",  3/8",  etc. 

Fig.  93  shows  the  calipers  closed.  Now  if  the  thimble 
is  rotated  one  complete  turn  it  will  open  .025".  This  brings  the 
end  of  the  thimble  to  the  first  graduation  on  the  sleeve  A, 
Fig.  94. 


FIG.  95 


If  it  is  desired  to  set  the  calipers  to  .037",  rotate  the 
thimble  an  additional  12  graduations,  as  in  Fig.  95. 

To  set  the  calipers  for  a  common  fraction,  as  31/32",  first 
find  the  decimal  equivalent.  31/32  =  .968+.  Rotate  the 


0    I    2    3  4    5    6   7 


FIG.  96 


thimble  D  to  the  number  9  graduation  on  the  sleeve  A;  this 
is  .900".  Then  to  the  second  graduation  past  the  number  9, 
which  is  .950";  then  beginning  with  zero,  rotate  the  thimble 
18  graduations  and  the  caliper  is  set  to  .968",  Fig.  96. 


TURNING  TOOL  FOR  BRASS  83 

CAUTION. — Never  use  the  micrometer  caliper  on  work 
while  it  is  turning  in  the  lathe. 

Knurling. — The  boss  at  the  end  of  B  is  used  as  a  handle 
so  that  if  it  were  left  smooth  it  would  be  hard  to  turn  by  hand. 
The  surface  is  therefore  made  rough  with  a  knurling  tool  as 
shown  in  Fig.  97.  After  piece  A  is  finished,  it  is  removed  from 
B  and  B  is  reversed  in  the  lathe  so  that  the  boss  can  be 
knurled. 

In  case  there  is  enough  room  between  the  dog  and  the 
work,  when  held  in  Fig.  89,  there  is  no  need  to  reverse  the 
work  for  knurling  since  it  can  be  done  in  this  position. 


\ 


FIG.  97 

The  speed  of  the  lathe  should  be  about  the  same  for  knur- 
ling as  for  thread  cutting.  If  the  lathe  runs  too  fast,  the 
knurling  tool  does  not  cut  satisfactorily. 

The  tool  is  set  so  that  the  face  of  the  rollers  is  parallel 
with  the  surface  to  be  knurled.  When  starting  the  cut,  the 
rollers  can  be  forced  into  the  piece  easier  if  about  half  of 
their  width  extends  past  the  end  of  the  work. 

The  knurling  tool  should  be  pressed  into  the  work  fast 
enough  so  that  about  one  half  the  depth  of  the  finished  knurl 
will  be  cut  while  the  lathe  makes  three  or  four  revolutions. 
If  the  tool  is  forced  in  too  slowly  it  will  cut  a  finer  knurled 
surface  than  the  rollers  are  intended  to  cut. 

The  tool  is  fed  along  the  surface  in  the  same  manner  as 
in  plain  turning.  The  speed  at  which  the  carriage  of  the  lathe 
moves  has  no  effect  upon  the  pitch  of  the  knurled  surface 
since  this  is  controlled  by  the  pitch  of  the  grooves  in  the 


84  LATHE  WORK 

rollers.     If  a  finer  knurled  surface  is  desired,  a  knurling  tool 
having  rollers  with  finer  grooves  would  have  to  be  used. 

Turning  Tool  for  Brass. — The  tools  used  for  cutting  brass 
are  very  much  the  same  as  for  other  work,  with  the  excep- 
tion that  the  cutting  edge  should  have  no  rake  or  lip ;  that  is, 
the  top  of  the  tool  should  be  in  a  horizontal  plane,  or  nearly 
so.  (A,  Fig.  98.)  This  is  very  important,  for  if  the  tool  has 
any  top  rake  or  lip,  as  is  usually  the  case  when  turning  iron 
or  steel,  it  is  very  apt  to  gouge  into  the  work. 


FIG.  98 

The  point  B  may  be  ground  with  sharp  corners  as  shown, 
or  rounding. 

Drilling  Brass. — Twist  drills,  as  they  come  from  the  fac- 
tory, are  ground  for  cutting  iron  and  steel;  in  this  condition 
they  are  not  suitable  for  drilling  brass  because  they  have  a 
tendency  to  gouge  into  the  work.  To  overcome  this,  the  lip 
at  the  cutting  edge  should  be  ground  straight  for  about  1/64" 
and  parallel  with  the  axis. 

Cutting  Speed. — When  cutting  brass  the  machine  is  run 
much  faster  than  for  cast  iron  or  steel, 


BRASS  PLUMB  BOB 
Problem  8. — Brass  Plumb  Bob  with  Steel  Point. 


85 


Ithltfcfci 

Vf 

i*  &>-~r — >K6 

FIG.  100 

Sequence  of  Operations: 

1.  Cut  off  piece  of  brass  rod  5/8"  diameter  and  23/8" 
long,  using  power  saw  or  a  cutting-off  tool  in  lathe. 

2.  Place   in   three-jaw   chuck   and   drill    7/16"   hole,   and 
5/32"  hole  with  straight-shank  drills  held  in  drill  chuck,  as 
in  Fig.  57,  page  50. 

The  drill  chuck  is  prevented  from  turning  by  the  tight  fit 
of  the  taper  shank.  Some  mechanics  wrap  one  thickness  of  a 
piece  of  paper  around  the  shank  to  make  it  hold  better.  The 
paper  also  protects  the  hole  in  the  tail-stock  spindle  from 
being  scored. 

3.  Finish  surface  D  with  boring  tool  and  cut  threads  with 
lathe  tool,  or  use  tap  as  in  Fig.  46,  page  42. 

Piece  B. 


FIG.  101 

1.     Cut  off  piece  of  cold-rolled  steel  1/4"  diameter,  13/16" 
long. 


86  LATHE  WORK 

2.  Mount  in  3-iaw  chuck.   Finish  surface  J  with  lathe  tool 
and  file.    The  end  should  be  slightly  tapered,  so  that  it  will 
just  enter  the  5/32"  hole;  the  remainder  of  the  surface  should 
be  a  little  larger  than  the  hole. 

3.  Force  it  in  piece  A  with  tail-stock  spindle  or  remove 
from  lathe  and  use  bench  vise. 

Piece  C. 


1.  Clamp  a  piece  of  5/8"  diameter  brass  rod  in  three- 
jaw  chuck  so  that  the   end   will   extend   out  from   the  jaws 
about  1". 

2.  Turn   surface   F,   and    also   where   the   threads   are   to 
be  cut  to  fit  D  in  Piece  A  (close  running  fit).     Turn  surface 
G  to  size. 

3.  Cut  threads  with  lathe  tool  or  use  die  as  in  Fig.  51, 
page  44. 


FIG.  103 

4.     Screw  A  on  C  and  finish  A  and  B ;  knurl  surfaces  G, 
piece  C,  and  F,  piece  A.    The  knurling  tool  shown  in  Fig.  103 


LATHE  WORK 


87 


is  recommended  for  light  work  such  as  this,  although  the 
one  shown  in  Fig.  97,  page  83,  or  a  hand  knurler  could  be 
used. 

5.  Unscrew. A  from  C  and  drill  the  3/8"  and  the  No.  56 
hole  in  piece  C.    The  point  of  the  3/8"  drill  should  be  ground 
thin  ;  this  will  cause  it  to  drill  a  hole  with  a  sharp  point  at 
the  extreme  end.     The  object  of  this  is  to  insure  the  small 
No.  56  drill  starting  true. 

6.  The  curved  surfaces  I.  H.  are  first  roughed  out  with 
a  cutting-off  tool,  then  finished  with  a  forming  tool,  Fig.  104. 

If  a  forming  tool  is  not  at  hand  the  piece  may  be  finished 
with  specially  ground  bits  held  in  the  regular  tool  holder. 
It  may  also  be  finished  with  lathe  scrapers  or  hand  tools. 

If  the  work  is  done  in  the  order  given  one  surface  will 
be  true  with  another. 


FIG.  104 


CHAPTER  VI 
SURVEY  OF  LATHE  AND  SHAPER  TOOLS 

Shape  of  Tools. — Authorities  differ  as  to  the  proper  shaped 
tools  for  cutting  metal.  This  is  probably  due  to  the  varying 
conditions  under  which  the  tools  are  used.  For  example,  if 
a  certain  tool  is  designed  for  cutting  steel,  this  tool  may  give 
excellent  results  in  a  large  lathe  turning  a  6"  steel  shaft, 
but  for  turning  a  1"  shaft,  and  in  a  small  lathe,  a  somewhat 
different  shaped  tool  might  give  better  results.  Again  a 
roughing  tool,  which  will  cut  off  the  maximum  amount  of 
metal,  may  be  too  blunt  and  clumsy  for  some  jobs. 

When  a  tool  is  to  be  used  repeatedly  on  the  same  kind  of 
work,  as  is  usually  the  case  in  a  manufacturing  shop,  it  is 
important  to  have  it  as  nearly  the  correct  shape  as  possible. 
But  in  an  ordinary  job  shop  where  the  character  of  work  is 
continually  changing  the  important  thing  is  to  get  the  work 
done.  In  this  case  the  desired  results  may  be  obtained  by 
using  whatever  tools  are  handy,  although  they  may  not  be 
exactly  suited  to  the  job. 

Lathe  and  shaper  tools  are  divided  into  two  general  classes, 
i.  e.,  forged  tools,  and  tools  or  bits  which  are  held  in  a  tool 
holder.  Forged  tools  are  more  rigid,  therefore  heavieY  cuts 
can  be  taken  and  they  are  less  liable  to  chatter.  They  can 
also  be  used  in  narrower  spaces.  Tools  held  in  tool  holders 
being  comparatively  smaller  are  cheaper  and  are  more  quickly 
sharpened.  Tool  holders  also  have  a  wide  range  of  applica- 
tion, as  any  number  of  different  shaped  tools  or  bits  can  be 
used  in  the  same  tool  holder. 

The  tools  described  in  this  book  are  mostly  of  the  tool- 
holder  type.  In  case  forged  tools  are  to  be  used  the  instruc- 
tions apply  equally  to  them,  for  there  is  practically  no  differ- 
ence between  the  two  types  of  tools  at  the  cutting  edge. 


HARDNESS  OF  TOOLS  89 

Steel  for  Cutting  Tools. — Cutting  tools  are  usually  made 
from  one  of  two  kinds  of  steel:  carbon  tool  steel,  or  high- 
speed steel. 

Carbon  tool  steel  has  been  in  use  for  centuries  and  is  still 
used  for  machine  shop  tools,  altho  high-speed  steel  has  to  a 
great  ex-tent  taken  its  place. 

A  tool  made  from  carbon  steel  produces  a  smoother  finish 
than  one  made  from  high-speed  steel,  because  it  can  be  sharp- 
ened with  a  keener  edge.  In  some  cases  this  is  important. 

Finishing  tools  used  in  a  tool  holder,  however,  are  gen- 
erally made  of  high-speed  steel,  and  if  properly  oil-stoned, 
will  cut  smooth  enough  for  most  purposes.  Finishing  tools 
are  also  forged  from  high-speed  steel. 

Carbon  steel  is  much  cheaper  and  is  easier  to  forge  than 
high-speed  steel,  which  sometimes  makes  it  preferable.  This 
is  especially  true  if  the  tools  made  from  it  are  to  be  used  only 
occasionally. 

Carbon  steel  can  be  more  easily  tempered  to  a  certain 
degree  of  hardness  than  high-speed  steel.  This  a  desirable 
feature  for  such  tools  as  chisels,  taps,  and  dies,  etc.  If  these 
tools  were  made  as  hard  as  lathe  and  shaper  tools  they  would 
not  withstand  the  shock  or  twisting  stresses. 

The  principal  objection  to  the  use  of  carbon  steel  is  that 
it  will  lose  its  temper,  or  hardness,  when  overheated.  This 
occurs  when  a  tool  is  forced  to  take  too  heavy  a  cut  or  too 
fast  a  cutting  speed;  in  either  case  the  friction  causes  the 
cutting  edge  to  heat  to  such  a  degree  that  it  becomes  blue 
and  it  will  no  longer  cut. 

High-speed  steel  will  not  loose  its  hardness  when  so 
heated,  thus  giving  it  a  distinct  advantage  when  used  for 
roughing  and  other  tools  that  are  intended  for  heavy  cuts 
or  for  high  cutting  speeds. 

High-speed  steel  is  expensive  and  it  is  hard  to  forge.  This 
is  the  principal  reason  why  it  is  used  so  extensively  in  tool 


90  SURVEY  OF  LATHE  AND  SHAPER  TOOLS 

holders.  Also  high-speed  steel  bits  for  tool  holders  are  hard- 
ened ready  for  use. 

How  to  Determine  the  Difference  Between  High-Speed 
Steel  and  Carbon  Steel. — A  practical  way  to  determine  the 
difference  between  high-speed  steel  and  carbon  steel  is  by 
comparing  the  color  of  the  sparks  when  grinding.  The  sparks 
from  high-speed  steel  are  much  darker  than  those  from  carbon 
steel. 

How  to  Determine  the  Hardness  of  Tools. — The  most  com- 
mon method  to  determine  if  a  tool  is  hard  or  soft,  is  by 
testing  it  with  a  file.  If  the  file  cuts  without  much  pressure 
the  tool  is  soft;  if  it  files  with  difficulty,  it  is  medium  hard; 
if  the  file  makes  no  impression  upon  the  steel,  it  is  hard. 

Rate  of  Feed. — The  rate  of  feed  for  small  lathe  and  shaper 
work  ranges  from  1/64"  to  1/32"  for  roughing  tools  and  lathe 
finishing  tools.  A  shaper  finishing  tool  is  usually  fed  faster. 

When  turning  large  work,  say  a  6"  shaft,  in  a  heavy  lathe, 
the  feed  for  the  roughing  cut  may  be  1/32"  to  1/8",  and  for 
the  finishing  cut  1/16"  to  1/4".  The  finishing  tool  has  a  wide 
cutting  edge.  In  order  to  produce  a  smooth  surface  the  tool 
must  be  sharp  and  a  lubricant  must  be  used. 

Depth  of  Cut. — The  depth  of  cut  for  a  roughing  tool  de- 
pends largely  upon  the  amount  of  metal  to  be  removed,  the 
rigidity  of  the  machine  and  work,  and  rate  of  feed.  When 
deep  cuts  are  taken  comparatively  fine  feeds  are  used,  and  for 
shallow  cut  coarse  feeds. 

The  depth  of  cut  for  a  finishing  tool  is  usually  just  deep 
enough  to  take  out  the  tool  marks  left  by  the  roughing  tool 
or  to  bring  the  work  to  size. 


Questions — Chapters  IV,  V  and  VI 

1.  Describe  the  three  different  kinds  of  taps  on  page  40 
and  their  uses. 

2.  Will  a  tap  follow  a  drilled  hole  true? 

3.  How  are  taps  used  in  a  lathe  ? 

4.  Which  is  the  starting  side  of  a  die? 

5.  What  is  the  difference  between  a  selective-head  lathe 
and  a  cone  pulley  lathe? 

6.  Describe  the   headstock,  tailstock  and  carriage  of  a 
lathe. 

7.  If  the  leadscrew  of  a  lathe  has  5  threads  per  inch, 
what  should  be  the  ratio  of  the  gearing  to  cut  a  screw 
with  14  threads  per  inch? 

8.  What  is  the  compound  rest  of  a  lathe  used  for? 

9.  Describe  the  different  kinds  of  lathe  chucks  in  com- 
mon use. 

10.  What  is  a  boring  bar  used  for? 

11.  Should  oil  be  used  when  threading  cast  iron? 

12.  Why  is  oil  used  on  a  mandrel  before  it  is  forced  into 
a  hole? 

13.  Describe  how  a  micrometer  caliper  will  measure  to  a 
thousandth  of  an  inch. 

14.  What  is  a  knurling  tool? 

15.  How  are  twist  drills  ground  for  cutting  brass? 

16.  What  is  a  forming  tool? 

17.  How   would   you   determine   the   difference   between 
high  speed  steel  and  carbon  steel? 


91 


CHAPTER  VII 
MILLING  MACHINE  WORK 

Description  of  Milling  Machines. — There  are  several  differ- 
ent kinds  of  milling  machines,  but  the  ones  most  commonly 
used  are  the  plain  miller  and  the  universal  miller.  Both  of 
these  machines  have  horizontal  spindles.  The  difference  be- 
tween them  is  that  the  table  of  the  plain  miller  can  be  moved 
only  at  right  angles  or  parallel  to  the  spindle,  while  the  table 
of  the  universal  miller  may  be  moved  at  different  angles. 
The  principal  advantage  of  the  universal  machine  occurs  in 
cutting  spiral  gears,  spiral  milling  cutters,  etc.  This  class  of 
work,  however,  will  not  be  treated  in  this  book. 

As  in  the  case  of  lathes,  there  are  several  makes  of  millers, 
all  of  which,  altho  varying  in  efficiency  and  utility,  employ 
the  same  fundamental  cutting  operations.  When  one  has 
become  familiar  with  the  operation  of  one  machine,  he  should 
be  able  to  operate  other  makes  of  different  design  with  very 
little  difficulty. 

Milling  machines  like  many  other  machine  tools  have 
either  a  cone  pulley  or  a  constant-speed  drive.  The  one  shown 
in  Fig.  105  has  a  constant-speed  drive. 

The  driving  pulley  is  at  the  left  of  the  machine. 

The  spindle  speed  changes  are  obtained  by  shifting  encased 
gears  near  the  driving  pulley.  This  is  done  by  means  of  the 
small  pilot  wheel  and  levers  on  the  gear  box.  The  long  hand 
lever  at  the  right  of  this  box  operates  the  clutch  for  starting 
and  stopping  the  machine. 

The  small  pilot  wheel  below,  together  with  the  two  levers 
on  either  side  of  it,  are  used  for  changing  the  feed.  The 
double-ended  V-shaped  lever  under  the  table  is  for  starting 
and  stopping  the  feed.  The  hand-crank  and  hand-wheel  at 

92 


MILLING  MACHINES 


93 


the  right  are  for  the  hand  cross  feeds  and  for  raising  and 
lowering  the  table. 


FIG.  105.    HIGH-POWER  UNIVERSAL  MILLER 


94  MILLING  MACHINE  WORK 

Problem  9. — Milling  a  Square  Casting. 


3. 
4. 

5. 


FIG.  106 

Sequence  of  Operations: 

1.  Grind  off  all  gates,  fins,  sand,  etc. 

2.  Clamp  in  vise  and  mill  side  A. 

Mill  sides  B  and  C  square  with  A. 

Mill  side  D  parallel  to  A. 

Mill  both  ends  square  with  the  other  sides. 
Object  of  Grinding  Rough  Casting. — The  outer  surface  of 
cast  iron  is  hard  and  more  or  less  covered  with  sand.  This 
would  dull  milling  cutters  even  more  quickly  than  it  would 
a  lathe  or  planer  tool.  As  milling  cutters  are  expensive  and 
require  more  time  to  sharpen,  greater  care  should  be  taken 
to  protect  their  cutting  edges.  It  is  not  necessary,  however, 
to  remove  all  of  the  scale,  but  the  casting  should  be  thor- 
oughly cleaned. 


FIG.  107 

Milling-Machine  Vise. — Fig.  107  shows  the  vise  used  in  the 
milling  machine.  It  has  a  graduated  swivel  base  so  that  it 
can  be  turned  at  different  angles. 


SPIRAL  MILLING  CUTTER 


95 


Clamping  the  Work. — The  work  is  held  in  the  milling 
machine  vise  as  shown  in  Fig.  108.  It  should  rest  on  two 
parallels  that  are  wide  enough  to  bring  the  surface  to  be  milled 


FIG.  108 

above  the  level  of  the  vise.  In  order  to  get  a  tighter  grip  on 
it,  heavy  paper  should  be  placed  between  it  and  the  jaws  of 
the  vise.  The  paper  will  also  protect  the  jaws  from  being 
marred  by  the  rough  sides  of  the  casting. 


FIG.  109 

The  Cutter. — Work  of  this  sort  is  milled  with  a  common 
spiral  milling  cutter,  Fig.  109.  As  these  cutters  are  made  in 
different  lengths,  one  should  be  selected  that  is  a  little  longer 
than  the  widest  surface  to  be  cut. 

The  Arbor. — All  milling-machine  arbors  are  provided  with 
collars,  Fig.  108,  of  different  lengths,  so  that  the  position  of 
a  cutter  on  them  may  be  varied.  These  collars  slip  loosely 
on  over  the  arbor  and,  when  the  nut  A  is  tightened,  clamp 
the  cutter  in  place. 

If  the  cutter  is  mounted  near  the  main  bearing  of  the 
milling-machine  spindle,  it  will  work  better  than  if  located 
near  the  outer  end. 


96  MILLING  MACHINE  WORK 

One  end  of  the  arbor  is  tapered  and  fits  into  the  spindle 
B.  It  may  be  withdrawn  by  tightening  the  nut  C.  The  end 
D  is  supported  by  an  out  port  bearing. 

Most  arbors  are  also  provided  with  a  keyway,  so  that  when 
heavy  cuts  are  to  be  taken  or  a  large  cutter  used  it  may  be 
keyed  to  the  arbor. 

CAUTION: — Beginners  are  cautioned  to  be  sure  that  the 
direction  of  rotation  and  speed  of  the  cutter  and  the  direction 
of  the  feed  are  correct  before  starting  a  cut. 

Direction  of  Cutter  Rotation. — Milling  cutters  are  all 
ground  with  Clearance  A,  Fig.  110-a,  and  if  rotated  in  the  wrong 
direction  will  not  cut.  Therefore,  before  mounting  the  cutter 
start  the  machine  and  note  the  direction  of  rotation  of  the 
arbor.  If  it  rotates  as  indicated  by  the  arrow  the  cutter  should 
be  mounted  as  shown.  If  the  cutter  were  mounted  as  in 
Fig.  110-b  it  would  not  cut. 


FIG.  110-a  FIG.  110-b 

Cutter  Speed. — The  maximum  cutting  or  surface  speed  for 
a  milling  cutter  made  of  carbon  steel  is  about  50'  to  60'  per 
minute  when  cutting  cast  iron.  Cutting  speed  is  the  velocity 
of  a  point  on  the  circumference  of  the  cutter.  Thus  a  cutter 
2  1/2"  in  diameter,  and  turning  90  revolutions  per  minute, 
will  have  a  cutting  speed  of  about  60'  per  minute. 

No  fixed  rule  can  be  given  for  the  proper  cutter  speed,  as 
too  much  depends  on  the  character  of  the  work,  the  hardness 
of  the  metal,  the  size  of  the  machines,  etc.  Machinists  de- 
termine the  proper  speeds  by  the  action  of  the  cutting  tool 
and  from  previous  experiences  on  work  similar  in  character. 


CUTTER  WORK  97 

It  will  be  necessary  for  the  instructor  to  designate  the 
speed  of  the  machine  until  the  student  has  had  sufficient 
practice  to  be  able  to  judge  fairly  well  for  himself.  It  is 
better  to  run  the  cutter  too  slow  than  too  fast,  for  if  it  is 
run  too  fast  it  will  soon  be  ruined. 


FIG.  Ill  FIG.  112 

Direction  of  Feed. — The  direction  of  the  feed  in  relation  to 
the  cutter  rotation  is  very  important.  Fig.  Ill  shows  the 
correct  way.  In  this  case  the  direction  of  the  feed  is  opposite 
to  the  rotation  of  the  cutter.  The  wrong  way  is  shown  in 
Fig.  112.  If  the  work  were  fed  in  this  manner,  the  cutter 
would  act  as  a  feed  roller  and  draw  the  work  in  faster  than 
it  would  cut.  This  would  break  the  teeth  of  the  cutter. 

Roughing  Cut. — The  roughing  cut  on  cast  iron  should 
always  be  deep  enough  to  get  under  the  scale;  in  this  case 
about  3/32"  or  1/8"  deep.  Cast  iron  and  brass  are  milled  dry 
but  on  steel  the  cutter  works  better  if  lard  oil  or  some  other 
lubricant  is  used. 

Rate  of  Feed. — As  in  the  case  of  the  cutter  speed,  no  fixed 
rule  can  be  given  for  the  rate  of  feed.  This  should  be  de- 
termined by  the  instructor.  It  may  be  stated,  however,  that 
.018"  feed  per  revolution  of  the  cutter  should  be  safe  in  this 
case.  If  a  good  machine  is  used  and  the  iron  is  soft  this  feed 
could  be  increased. 

Finishing  Cut. — The  depth  of  the  finishing  cut  can  be  any- 
thing up  to  1/32".  If  more  than  this  is  taken  off,  the  surface 
may  not  be  uniform.  The  same  cutter  speed  as  for  roughing 
can  be  maintained  but  the  feed  should  be  increased.  If  a 


98 


MILLING  MACHINE  WORK 


large  surface  is  to  be  finished  and  the  iron  is  soft,  it  will  pay, 
in  the  amount  of  time  saved,  to  increase  both  the  speed  and 
the  feed. 

After  side  A,  Fig.  106,  is  finished,  the  sides  B  and  C  are 
milled  square  with  A.  D  is  then  milled  parallel  with  A. 
The  method  of  clamping  the  work  in  the  vise  is  practically 
the  same  as  that  used  for  the  shaper  work. 


FIG.  113 

Milling  the  Ends. — If,  in  milling  the  ends,  the  block  extends 
so  far  above  the  jaws  of  the  vise  that  the  action  of  the  cutter 
has  a  tendency  to  tip  it,  turn  the  vise  through  90°  and  clamp 
it  edgewise  as  shown  in  Fig.  113. 


MILLING  A  CONCAVE  SURFACE  99 

Problem  10. — Milling  a  Concave  Surface,  Recess,  etc. 


i  ij  j*s-?!  !!  i,. ,  ^ — 5-- 


FIG.  114 

Sequence  of  Operations : 

1.  Mill  the  recess  A  and  the  slot  B  with  a  5/8"  end  mill. 

2.  Mill  the  corners  D  and  E  with  a  side-milling  cutter. 

3.  Mill  the  grooves  in  the  bottom  with  a  3/8"  milling 
cutter. 

4.  Mill  the  concave  sides  with  a  forming  cutter. 
Milling  the  Recess  and  Slot. — (Problem  9  is  to  be  used  for 

this  problem.)  The  recess  A  and  the  slot  B  are  good  examples 
of  the  kind  of  work  for  which  the  end  mill  is  particularly 
adapted.  However,  this  tool  is  also  used  for  other  kinds  of 
work. 


FIG.  115 

The  end  mill,  Fig.  115,  has  a  taper  shank  and  is  mounted 
in  the  spindle  of  the  milling  machine  in  the  same  manner  as 
a  drill  in  a  drill  press.  These  shanks  have  either  the  Morse 
taper  or  the  Brown  &  Sharpe  taper.  The  Morse  standard 
taper  is  used  for  drills  as  well  as  for  end  mills.  The  taper 
of  the  Brown  &  Sharpe  standard  is  less  than  the  Morsq 


100 


MILLING  MACHINE  WORK 


standard.  For  this  reason  the  shanks  of  end  mills  used  in 
milling  machines  usually  have  the  Brown  &  Sharpe  taper  as 
they  will  stay  in  the  spindle  better. 


FIG.  116 


Clamping  the  Work. — Lay  off  the  outline  of  the  recess  on 
the  surface  of  the  block  and  clamp  it  square  in  the  vise  as 
in  Fig.  116.  Adjust  the  position  of  the  block  until  the  end 
of  the  mill  is  just  touching  the  surface  at  one  corner  of  the 
recess.  In  order  to  determine  when  the  recess  has  been  cut 
to  the  full  depth,  set  the  dial  on  the  cross  slide  to  the  zero 
point.  This  dial  is  graduated  in  thousandths  of  an  inch. 

Depth  of  Cut. — Force  the  end  of  the  mill  into  the  surface 
for  about  .03"  and  feed  the  work  by  hand  so  that  the  mill  will 
cut  just  inside  of  the  outline  marked.  Repeat  this  operation 
until  the  cross-feed  dial  reads  .250",  the  required  depth  of  the 
recess. 

End  mills  usually  work  better  with  shallow  cuts  and 
coarse  feeds  than  with  deep  cuts  and  fine  feeds.  Another 
reason  for  taking  shallow  cuts  in  this  case  is  because  there 
are  no  teeth  at  the  center  of  the  cutting  end  A,  Fig.  115. 
This  makes  it  hard  to  force  the  tool  into  the  metal. 

Speed  of  Cutter. — As  this  cutter  is  much  smaller  in  diam- 
eter than  the  spiral  mill  used  in  Problem  9  the  spindle  speed 
may  be  increased. 

Milling  the  Slot. — The  slot  is  to  be  milled  with  the  same 
end  mill  that  was  used  for  cutting  the  recess.  Before  starting 
this  cut,  remove  the  work  from  the  vise  and  drill  a  1/2"  hole 
as  shown  at  H,  Fig.  117.  This  hole  is  necessary  on  account 


GANG  MILLING 


101 


of  the  center  of  the  end  mill  having  no  teeth. 

After  reclamping  the  work  in  the  vise  adjust  it  so  the 
mill  will  be  at  the  end  of  the  slot  where  the  hole  has  been 
drilled.  Feed  the  cutter  thru  the  block,  Fig.  118,  as  far  as  the 
cutting  edges  will  permit.  It  cuts  better  in  this  position  than 
at  the  outer  end. 


FIG.  117 


FIG.  118 


Now  feed  the  work  horizontally  until  the  cutter  reaches 
the  other  end  of  the  slot. 

Rate  of  Feed. — If  the  automatic  feed  is  used  it  should  be 
very  fine.  The  safest  way  for  beginners  is  to  feed  it  by  hand. 
If  too  coarse  a  feed  is  used  the  cutter  will  break. 

Direction  of  Feed. — When  cutting  a  slot  like  this,  where 
half  of  the  circumference  of  the  mill  is  in  contact  with  the 
metal,  and  when  using  the  end  of  the  mill  as  in  cutting  the 
recess,  the  feed  may  be  in  either  direction. 

Gang  Milling. — When  two  or  more  cutters  are  used  on  one 
spindle  at  the  same  time  it  is  called  gang  milling.  The  cor- 


FIG.  119 


FIG.  120 


ners  E  and  D  of  this  problem  may  be  milled  by  first  cutting 
one  and  then  the  other  with  a  side-milling  cutter  shown  in 
Fig.  119.  But  if  a  large  number  of  these  pieces  were  to  be 


102  MILLING  MACHINE  WORK 

made,  two  cutters  would  be  used,  Fig.  120,  with  the  collar  I 
between  them  so  that  they  will  be  the  proper  distance  apart. 

A  third  method  is  to  use  a  cutter  between  the  side  mills 
instead  of  a  collar.  If  this  method  is  used  the  surface  should 
not  be  milled  when  squaring  the  block  in  Problem  9. 

Depth  of  Cut. — When  using  gang  cutters  the  required 
depth  is  usually  cut  at  one  time.  To  set  the  work  for  the 
depth  shown  in  Fig.  114,  bring  the  work  up  under  the  revolv- 
ing cutter  until  it  just  touches.  Then  move  the  work  clear 
of  the  cutter  and  raise  it  3/16"  or  .187",  using  the  graduated 
dial  on  the  elevating  shaft. 

Cutting  Speed. — The  speed  of  the  machine  for  gang  cutting 
is  determined  by  the  diameter  of  the  largest  cutter. 

Groove  Cutting. — The  two  3/8"  grooves  in  this  problem 
may  be  cut  with  one  or  two  keyway  cutters. 

The  difference  between  this  cutter  and  the  side-milling 
cutter  is  that  it  has  no  cutting  edges  on  the  side.  It  is  used 
principally  for  cutting  grooves  like  these  and  for  cutting 
standard  keyways  in  shafts. 


FIG.  121.    CONVEX  CUTTER  FIG.     122.     CONCAVE  CUTTER 

Forming  Cutters. — Cutters  having  curved  or  irregular  cut- 
ting edges  are  usually  called  formed  cutters.  The  one  used 
for  the  concave  surface  in  this  problem  might  be  classed  as 
such,  but  is  usually  called  a  convex  cutter.  Fig.  121. 

When  cutting  the  concave  surface  in  the  end  of  the  block 
it  will  be  less  liable  to  slip  if  clamped  edgewise  in  the  vise. 


DIVIDING  HEAD  AND  TAILSTOCK 
Dividing  Head  ?.nd  Tailstock 


103 


FIG.  123 


Fig.  123  shows  a  dividing  head  and  tailstock.  The  tail- 
stock  is  used  for  holding  the  ends  of  shafts,  mandrels,  etc. 
The  small  jack  shown  is  for  supporting  the  middle  of  long 
slender  work  when  mounted  between  the  centers. 

The  Dividing  Head. — The  dividing  head  is  used  for  accur- 
ately spacing  or  dividing  the  circumference  of  a  piece  of  work 
into  any  number  of  parts,  as  in  squaring  a  shaft,  gear  cutting, 
etc. 

The  center  and  slotted  arm  are  made  in  one  piece  and  like 
a  lathe  center  are  held  in  the  spindle  of  the  dividing  head  by 
a  taper  fit.  The  slot  in  the  arm  is  to  receive  the  tail  of  a 
lathe  dog  so  that  work  mounted  between  the  centers  will 
rotate  with  the  spindle  of  the  dividing  head.  The  set  screw 
at  the  end  of  the  slot  is  to  take  up  the  slack  or  lost  motion 
between  the  sides  of  the  slot  and  the  tail  of  the  lathe  dog. 

The  spindle  of  the  dividing  head  is  threaded  like  a  lathe 
spindle  so  that  a  chuck  may  be  screwed  on  it. 

The  Index  Plate. — The  round  plate  with  a  number  of 
circles  of  holes  on  the  side  of  the  dividing  head  is  called 
the  index  plate. 


104  MILLING  MAC HIN E  WORK 

Index  Crank. — The  index  crank  is  in  front  of  the  index 
plate  and  is  provided  with  a  slot  so  that  by  loosening  the 
hexagonal  nut  at  the  center  it  may  be  moved  to  different 
positions. 

Index  Pin. — At  the  end  of  the  index  crank  is  the  index  pin. 
One  end  of  this  pin  is  of  such  size  that  it  just  fits  into  the 
holes  in  the  index  plate.  The  other  end  has  a  knurled  knob 
which  is  used  to  withdraw  the  pin  so  that  the  crank  may  be 
turned. 

Indexing. — The  shaft  on  which  the  index  crank  is  mounted 
is  geared  to  the  spindle  of  the  dividing  head  at  a  ratio  of 
40  to  1.  Therefore,  40  turns  of  the  crank  will  cause  the  spindle 
to  make  one  complete  revolution. 

If  it  were  desired  to  make  4  divisions,  as  in  squaring  a 
shaft,  the  number  of  turns  of  the  crank  would  be  40  -=-  4,  or 
10  revolutions  for  each  cut.  To  make  40  divisions,  as  in  a 
40-tooth  gear  wheel,  the  crank  would  be  turned  one  revolution 
for  each  tooth. 

In  case  32  divisions  are  to  be  made,  the  turns  of  the  crank 
per  division  would  be  40/32  or  1  1/4  revolutions.  To  turn 
the  crank  1/4  of  a  revolution  a  circle  of  holes  is  selected  that 
is  evenly  divided  by  4,  as  24,  36,  etc.  If  the  24-hole  circle 
is  used,  the  crank  should  be  turned  6  holes  exclusive  of  the 
hole  the  index  pin  is  in.  Therefore  to  make  one  of  the  32 
divisions  the  index  crank  is  turned  1  revolution  plus  6  holes 
on  the  24-hole  circle. 

The  Sector. — All  dividing  heads 
are  provided  with  a  sector  which 
eliminates  counting  the  holes  in  the 
index  plate  each  time  a  division  is 
made. 

By  loosening  the  screw  A,  Fig. 
124,  the  arms  D  and  E  may  be  ad- 
justed to  include  any  desired  num- 

FIG.  124 


USE  FOR  THE  DIVIDING  HEAD 


105 


her  of  holes.  Thus  to  turn  the  index  crank  1/4  of  a  revolu- 
tion on  a  24-hole  circle  the  index  pin  should  be  rotated  from 
B  to  C. 


FIG.  125 


Examples  of  Use  for  the  Dividing  Head. — Fig.  125  shows 
the  method  of  cutting  spur  gears.  The  gear  blank  is  mounted 
on  a  special  mandrel.  The  mandrel  is  supported  between  the 
centers  of  the  dividing  head.  The  divisions  are  made  by  turn- 
ing the  index  crank.  The  cutfer  used  is  a  gear-tooth  cutter. 

An  example   of  accurate   indexing  is   shown  in   Fig.   126. 


106 


MILLING  MACHINE  WORK 


Thirty-six  1/4"  holes  arc  to  be  equally  spaced  on  the  cir- 
cumference of  a  19"  disc.  They  are  first  drilled  with  a  short 
drill  a  little  under  size  and  are  then  finished  to  size  with  a 
1/4"  end  mill. 


FIG.  126 

This  figure  also  shows  the  method  of  handling  work  larger 
than  the  dividing  head  will  swing  when  the  spindle  is  in  the 
horizontal  position.  In  this  case  the  dividing-head  spindle  has 
been  turned  through  an  angle  of  90°. 


Spur  Gears  and  Rack 

Gears  whose  tooth  elements  are  parallel  with  their  axis  are 
known  as  spur  gears.  They  are  also  called  straight-faced 
gears. 


SPUR  GEARS  AXD  RACK  107 

There  are  several  different  systems  of  gear-teeth  outlines, 
but  the  one  most  commonly  used  is  the  involute  system.  This 
system  requires  onlv  eight  cutters  for  each  pitch  and  has  a 
wide  application. 

The  operator  of  a  milling  machine  should  become  familiar 
with  the  following  terms :  the  pitch  circle,  the  pitch  diameter, 
the  circular  pitch  and  the  diametral  pitch. 

Pitch  Circle. — The  size  of  a  gear  is  determined  by  the 
pitch  circle,  C,  Fig.  127. 


FIG.  127 

Pitch  Diameter. — The  pitch  diameter  is  the  diameter  of  the 
pitch  circle,  D,  Fig.  127. 

Circular  Pitch. — The  circular  pitch  is  the  distance  from  the 
center  of  one  tooth  to  the  center  of  the  adjoining  tooth  meas- 
ured on  the  pitch  circle,  B.,  Fig.  127. 

Diametral  Pitch. — The  diametral  pitch  is  the  number  of 
teeth  per  inch  of  pitch  diameter.  It  therefore  determines  the 
size  of  the  teeth. 

For  example,  a  gear  with  12  teeth  and  a  pitch  diameter 
of  2",  will  have  a  diametral  pitch  of  6.  One  with  16  teeth 
and  the  same  pitch  diameter  will  have  a  diametral  pitch  of  8. 
Of  these  two  gears  the  teeth  on  the  16-tooth  gear  will  neces- 
sarily be  smaller  than  those  on  the  12-tooth  gear. 

The  distance  A,  Fig.  127,  is  the  reciprocal  of  the  diam- 
etral pitch.  Thus  on  an  8  diametral  pitch  gear,  the  distance 
A  is  1/8". 


108 


MILLING  MACHINE  WORK 


The  diametral  pitch  will  hereafter  be  referred  to  as  the 
pitch. 

Shape  of  Tooth. — The  thickness  of  the  tooth  on  the  pitch 
circle  is  the  same  in  all    sizes  of  gears  having  the  same  pitch. 
The  shape  of  the  tooth,  however,  varies  with  the  size  of  the 
gear;  that  is,  the  curve  on  the  side  of  a  tooth  on 
a  12-tooth  gear  is  a  little  difterent  from  that  on  a 
gear  having  13  teeth.       The  greatest  contrast  is 
noted  between  a  12-tooth  gear  and  a  rack,  Fig.  127. 

When  gear  wheels  are  cut  in  a  milling  machine 
a  formed  cutter,  Fig.  128,  having  the  same  profile 
as  the  space  between  the  teeth  is  used.  If  it  were 
necessary  to  cut  the  teeth  theoretically  correct,  a 
different  cutter  would  be  required  for  each  different 
size  gear.  In  practice,  however,  for  the  involute 
system  only  8  cutters  are  used  for  each  pitch.  The 
following  table  gives  the  range  of  each  cutter. 
No.  1  will  cut  wheels  from  135  teeth  to  a  rack. 


FIG.  128 


55 
35 
26 
21 
17 
14 
12 


134  teeth,  inclusive. 

54  " 

34  " 

25  " 

20  " 

16  " 

13  " 


For  example,  if  it  is  desired  to  cut  a  10-pitch  gear  with  28 
teeth,  a  10-pitch,  No.  4  cutter  should  be  used. 

Rack. — The  teeth  of  a  rack  are  developed  along  a  straight 
line  and  mesh  with  a  gear  having  the  same  pitch. 


RULES  FOR  SPUR  GEARS  109 

Rules  for  Computing  Spur  Gears 

DIAMETRAL  PITCH  required,  circular  pitch  given.  Divide  3.1416  by 
the  circular  pitch. 

EXAMPLE.  If  the  circular  pitch  is  2  inches,  divide  3.1416  by  2  and  the 
quotient,  1.5708,  is  the  diametral  pitch. 

DIAMETRAL  PITCH  required,  number  of  teeth  and  outside  diameter 

given.    Add  2  to  the  number  of  teeth  and  divide  by  the  outside  diameter. 

EXAMPLE.     If  the  number  of  teeth  is  40,  the  diameter  of  the  blank  is 

10^" ;  add  2  to  the  number  of  teeth,  making  42,  and  divide  by  10j^ ; 

the  quotient,  4,  is  the  diametral  pitch. 

CIRCULAR  PITCH  required,  diametral  pitch  given.  Divide  3.1416  by 
the  diametral  pitch. 

EXAMPLE.  If  the  diametral  pitch  is  4,  divide  3.1416  by  4  And  the 
quotient,  .785",  is  the  circular  pitch. 

NUMBER  OF  TEETH  required,  pitch  diameter  and  diametral  pitch 
given.  Multiply  the  pitch  diameter  by  the  diametral  pitch. 

EXAMPLE.  If  the  diameter  of  the  pitch  circle  is  10"  and  the  diametral 
pitch  is  4,  multiply  10  by  4  and  the  product,  40,  will  be  the  number  of 
teeth  in  the  gear. 

NUMBER  OF  TEETH  required,  outside  diameter  and  diametral  pitch 
given.  Multiply  the  outside  diameter  by  the  diametral  pitch  and  sub- 
tract 2. 

EXAMPLE.  If  the  whole  diameter  is  10^"  and  the  diametral  pitch  is  4, 
multiply  10^  by  4  and  the  product,  42  less  2,  or  40,  is  the  number  of 
teeth. 

PITCH  DIAMETER  required,  number  of  teeth  and  diametral  pitch  given. 
Divide  the  number  of  teeth  by  the  diametral  pitch. 

EXAMPLE.     If  the  number  of  teeth  is  40  and  the  diametral  pitch  is  4r 
divide  40  by  4  and  the  quotient,  10,  is  the  pitch  diameter. 
OUTSIDE  DIAMETER  or  size  of  gear  blank  required,  number  of  teeth 
and  diametral  pitch  given.    Add  2  to  the  number  of  teeth  and  divide  by 
the  diametral  pitch. 

EXAMPLE.  If  the  number  of  teeth  is  40  and  the, diametral  pitch  is  4, 
add  2  to  the  40,  making  42,  and  divide  by  4;  the  quotient,  lQl/2,  is  the 
whole  diameter  of  the  gear  or  blank. 


110  MILLING  MACHINED  WORK 

Problem  11.—  Gear  Cutting. 


25  T.   12  R    H5H 
FIG.  129 

Sequence  of  Operations  : 

1.  Select  cutter  and  mount  on  milling-machine  arbor. 

2.  Line  up  center  of  cutter  with  center  of  the  dividing 
head. 

3.  Place  gear  blank  on  mandrel  and  mount  mandrel  be- 
tween centers  of  the  dividing  head  and  the  tailstock. 

4.  Set  cutter  to  proper  depth. 

5.  Set  the  index  crank  and  sector  on  dividing  head  for 
25  divisions. 

Selecting  Cutter.  —  The  number  of  teeth  to  be  cut  in  this 
gear  is  25.  Referring  to  the  table  on  page  108  it  is  seen  that 
a  number  5  cutter  has  the  proper  range. 

Mounting  Cutter.  —  The  cutter  is  mounted  on  the  milling 
machine  arbor  as  close  to  the  main  bearing  of  the  spindle  as 
possible  and  yet  far  enough  away  to  have  it  line  up  with  the 
center  of  the  dividing  head. 

Centering  Cutter.  —  In  order  to  cut  the  teeth  radially  the 
center  of  the  cutter  must  be  in  line  with  the  center  of  the 
dividing  head.  All  gear  cutters  are  marked  with  a  center 
line  so  that  by  moving  the  dividing  head  close  to  the  cutter 
and  adjusting  the  position  of  the  table  they  may  be  accurately 
centered. 

Placing  Gear  on  Mandrel.  —  Gear  blanks  are  usually 
mounted  on  a  gear  mandrel,  Fig.  130. 

This  mandrel  is  not  tapered,  the  clamping  being  done  by 
means  of  the  nut  A.  By  removing  the  collars  B  B  several 
gears  can  be  mounted  at  one  time. 


DEPTH  OF  CUT 


111 


Mounting  the  Gear  Mandrel.— A  milling-machine  dog  or  a 
lathe  dog  is  fastened  on  one  end  of  the  mandrel.  The  latter 
is  then  mounted  between  the  dividing-head  center  and  the 


FIG.  130 


tailstock  center  in  the  manner  shown  in  Fig.  125.  Oil  should 
be  used  on  the  tail-stock  center.  The  set  screw  in  the  slotted 
arm  of  the  dividing  head  is  screwed  against  the  tail  of  the 
dog  to  prevent  any  lost  motion. 

Depth  of  Cut. — When  cutting  gear  teeth  of  this  size  all  of 
the  stock  is  removed  at  one  cut.  For  gears  with  large  teeth, 
say  of  4  or  5  pitch  and  larger,  it  may  be  necessary  to  take 
two  cuts. 

To  set  the  work  so  that  the  cutter  will  cut  the  proper 
depth,  start  the  machine  and  raise  the  work  up  under  the 
revolving  cutter  until  it  just  touches.  Move  the  work  clear 
of  the  cutter  and  set  the  dial  on  the  elevating  shaft  to  zero. 
Now  raise  the  table  .180"  as  indicated  by  the  graduations  on 
the  dial.  This  is  the  proper  depth  for  a  12-pitch  gear  tooth. 

All  milling  machines  are  provided  with  a  chart  that  gives 
the  depth  to  be  cut  and  the  range  of  the  cutters  for  all  sizes 
of  gears.  The  side  of  each  cutter  is  also  marked'  with  this 
information  for  its  particular  pitch  and  range. 

Setting  the  Index  Crank. — There  is  a  clamping  nut  on  the 
side  of  the  dividing  head  opposite  the  index  plate  which  should 
always  be  loosened  before  turning  the  index  crank  and  tight- 
ened after  indexing.  In  order  to  index  25  teeth,  the  crank 
must  be  turned  1/25  of  40,  or  1  3/5  turns  per  tooth.  3/5  of 
a  revolution  can  be  measured  on  a  circle  of  holes  which  is  a 
multiple  of  5, .as  20,  25,  30,  35,  etc.  Assume  the  use  of  the 


112 


MILLING  MACHINE  WORK 


30-hole  circle,  3/5  of  a  revolution  will  be  represented  by  18 
spaces. 

Loosen  the  nut  B,  Fig.  131,  and  adjust  the  index  pin  C 
in  one  of  the  holes  of  the  30-hole  circle.  Now  tighten  the  nut 
B  just  enough  to  hold  the  crank  in  position  and  pull  out  the 
index  pin  to  see  if  it  will  drop  into  the  hole  without  binding. 
If  the  index  pin  is  not  in  line  with  the  hole  its  position  may 
be  changed  slightly  by  rapping  the  end  of  the  index  crank 
with  a  piece  of  wood.  If  a  light  rap  is  not  sufficient  loosen 
the  nut  a  little.  After  the  index  pin  is  properly  set,  tighten 
the  nut  B  so  that  it  will  stay  in  this  position. 

Setting  the  Sector. — Loosen 
the  clamping  screw  A  on  the  sec- 
tor, Fig.  131,  and  move  the  arm 
D  so  that  the  beveled  edge  rests 
against  index  pin  C.  Withdraw 
the  index  pin  and  turn  the  crank 
to  the  right  18  holes,  not  count- 
ing the  hole  the  pin  was  in.  With- 
out changing  the  position  of  the 
arm  D  move  the  other  arm  E 
until  its  beveled  edge  strikes  the 
index  pin  in  its  new  position  at 
the  18th  hole.  Tighten  the  screw  A.  The  sector  is  now  set 
to  include  3/5  of  a  turn,  or  18  spaces. 

Indexing. — Before  taking  the  first  cut,  turn  the  index  crank 
clockwise  one  complete  revolution.  This  will  take  out  all 
the  slack  or  lost  motion  in  the  dividing  head. 

To  index  the  gear  for  the  next  cut  rotate  the  sector  arm 
D  up  to  the  index  pin.  Withdraw  the  pin  and  give  the  crank 
one  turn  to  the  right  or  clockwise,  plus  the  fraction  of  a  turn 
included  between  the  sector  arms.  This  operation  is  repeated 
until  the  gear  is  finished. 

Cutting  a  Rack. — The  size  of  the  teeth  of  a  rack,  as  with 
spur  gears,  is  designated  by  the  pitch. 


FIG.  131 


CUTTING  A  RACK 


113 


To  space  the  teeth  it  is  necessary  to  know  the  distance 
from  the  center  of  one  tooth  to  the  center  of  the  adjoining 
one.  For  a  12-pitch  rack  this  is  the  same  as  the  circular  pitch 


FIG.  132 

of   12-pitch  spur  gears.     The  circular  pitch  is  obtained  by 

dividing  3.1416  by  the   diametral  pitch.     With  a  diametral 

pitch  of  12  the  circular  pitch  is  .262".     The  following  table 

gives   the   diametral  pitches   commonly  used   and  the   corre- 

sponding circular  pitches. 

Diametral 

Pitch 


1/2 

134 

2 

2M 

2/2 

234 
3 


Circular 

Diametral 

Circular 

Pitch 

Pitch 

Pitch 

2.5133 

10 

.314 

2.0944 

11 

.286 

1.7952 

12 

.262 

1.571 

14 

.224 

1.3% 

16 

.1% 

1.257 

18 

.175 

1.142 

20 

.157 

1.047 

22 

.143 

.898 

24 

.131 

.785 

26 

.121 

.628 

28 

.112 

.524 

30 

.105 

.449 

32 

.098 

.393 

36 

.087 

.349 

40 

.079 

48 

.065 

114  MILLING  MACHINE  WORK 

Clamp  the  rack  blank  in  the  milling-machine  vise  on  a 
parallel  as  shown  in  Fig.  132.  After  taking  the  first  cut  of 
the  required  depth,  set  the  dial  on  the  cross  feed  to  zero.  Move 
the  table  horizontally  .262"  as  indicated  by  the  dial  on  the 
hand  crank.  Take  another  cut  and  continue  this  operation 
until  the  rack  is  finished.  If  one  end  of  the  rack,  as  A,  ex- 
tends beyond  the  vise,  it  will  be  necessary  to  reset  the  work 
as  the  cutter  will  not  cut  satisfactorily  with  such  poor  support. 


Questions 

(1)  If  the  live  lathe  center  runs  out  of  true  what  effect 
does  it  have  on  the  work? 

(2)  If  the  dead  center  is  out  of  true  what  is  the  effect? 

(3)  What  kind  of  a  file  should  be  used  for  lathe  work? 

(4)  Describe  how  to  center,  turn,  and  thread  a  bolt  in 
the  lathe,  as  per  sketch,  Fig.  133.    The  bolt  to  be  made  from 
a  hexagon  bar  of  cold-rolled  steel. 


JOT. 


A'- 

FIG.  133 


(5)  What  is  the  difference  between  a  shell  reamer  and  a 
rose  reamer? 

(6)  Why  is  a  flat  drill  used  to  rough  out  a  core  hole  in- 
stead of  a  twist  drill? 

(7)  Should  oil  ever  be  used  when  reaming  a  hole? 

(8)  What  is  the  difference  between  a  tool  used  for  turn- 
ing brass  and  one  for  cast  iron? 

(9)  When  cutting  metal  withxany  tool,  if  the  cutting  edge 
breaks  down  it  is  usually  due  to  one  of  the  following  causes : 
Machine  running  too  fast,  too  heavy  a  cut,  the  metal  being 
too  hard,  the  cutting  tool  too  soft,  or  it  is  improperly  set  in 
the  tool  post.     How  could  it  be  determined  which  one  of  the 
above  caused  the  trouble? 

(10)  How    would    you    machine    pulley    as    per    sketch, 
Fig.  134? 

115 


116 


QUESTIONS 


(11)  What  kind  of  steel  is  used  for  making  chisels,  and 
why? 

(12)  What  is  meant  by  the  cut  of  a  file? 

^viVvVsV^Otrj    — 


FIG.  134 

(13)  What  is  the  object  of  scraping  any  surface?     Give 
an  example  other  than  that  given  in  the  book. 

(14)  Why  is  the  finishing  tool,  Fig.   18,  made  wide  in- 
stead of  narrow? 

(15)  Why  are  shaper  tools  ground  with   less  clearance 
than  lathe  tools? 

(16)  Describe   how   to   machine   piece    of   work,    as   per 
sketch,  Fig.  135,  in  a  shaper. 


(17)  How  are   drills  sharpened,   and  are   they   made  of 
carbon  steel  or  high-speed  steel? 

(18)  What  is  the  advantage  of  having  drills  with  taper 
shanks? 

(19)  Describe  how  to  drill  and  tap  the  journal  bearing 
as  per  sketch,  Fig.  136. 

(20)  What  are  the  advantages  of  a  milling  machine  com- 
pared with  a  shaper? 


QUESTIONS 


117 


(21)     What  usually  occurs  when  the  work  is  fed  in  the 
same  direction  that  the  milling  cutter  rotates? 

I 


Cap  Screv 


"*-»m     rh 


FIG.  136 

(22)     How  would  you  mill  a  keyway  in  a  shaft  as  per 
sketch,  Fig.  137? 

k-  -A----A  jii. 


L_T1D 


FIG.  137 

(23)     How    would    you    mill    200   pieces    as   per    sketch, 
Fig.  138? 


5"- 


FIG.  138 


(24)     Describe  how  to  mill  a  slot  in  a  piece  of  work  as  per 
sketch,  Fig.  139. 

T  ' 


FIG.  139 


(25)     How  would  you  cut  a  spur  gear  with  20  teeth  8 
pitch? 


INDEX 


Accurate  boring  with  boring  bar  73 

Alignment  of  lathe  centers 54 

Angles  of  lathe  centers 50 

Angle  cutting,  in  lathe 74,  79 

in  shape r 28 

Arbor  or  mandrel,  gear 110 

lathe 78 

making  of 78 

milling  machine 95,  111 

mounting  work  on 78 

use  of 77 

Back  gears  of  lathe,  use  of. ...  68 

Bolt  threading,  hand 43 

machine  44 

Boring  bar,  use  of 69 

Boring  hole,  with  twist  drill  in 

lathe 75 

with  flat  or  lathe  drill 68 

Brass  turning 84 

Calipers,  firm  joint 57 

micrometer  80 

spring 70 

thread,  use  of 79 

Cast  iron,  turning 66-84 

planing 18-30 

Center  gouge,  use  of 39 

Center  punch,  use  of 34 

Centers  of  lathe,  alignment  of . .  54 

angle  of 50 

Centering  flat  drill  in  lathe 67 

Centering  shaft,  accurately 50 

combination  drill  and  coun- 
tersink for 50 

in  drill  press 50 

in  lathe 50 

lathe  tool  for 50 

Centering  twist  drill,  in  center 

of  circle 39 

in  lathe 75 

Centering    gear    tooth    milling 

cutter  110 


Change  gears,  common 60 

computing  for   thread   cut- 
ting    59 

patent  quick  change 46,  49 

Chattering,     cause    of,     boring 

tool 69 

shaper  finishing  tool 22 

Chisels,  cape,  flat 10 

round  nose  or  center  gouge  39 

sharpening  10 

use  of 10 

Chipping,  cast  iron 9 

Chucks,  centering  work  in 67 

description  of 66 

kinds  of 66 

Chucks,  drill,  use  in  drill  press .  36 

use  in  lathe 50 

Chuck  work 66-77 

Chucking,  advantage  of  proper  67 

Compound  rest  of  lathe 47,  62 

use  of,  for  thread  cutting. .  64 

angle  cutting 68,  79 

Concave  cutter 102 

Convex  cutter 102 

Cutting  recess,  in  steel  shaft. ...  57 

with  boring  bar 70 

with  end  mill 99 

Cutters,  milling  machine 

95,  99,  102,  108 

Cutting-off  tool 57 

Cutting  off  steel 49 

Cutting  threads,  brass 85-87 

cast  iron 73,  79 

steel 58-65 

with  die 43 

with  tap 41 

Die  and  stock 43 

hand  use 43 

use  in  lathe 44 

Die  stock 43 

Dies,  threading 42 

Diametral  pitch  of  gear  tooth. .  107 
Direction  of  rotation  of  milling 

cutters  96 


119 


120 


INDEX 


Dividers,  use  of 35 

Dividing  head 103 

examples  of  use  of 105 

illustration  of 103 

indexing  with 104,  112 

.     index  crank 104 

index  plate 103 

sector 104 

Dog,  use  of,  in  lathe 51 

Drill  bushing  or  sleeve 37 

Drill  chuck 50 

Drill  socket,  use  of 71,  75 

Drill  press,  description  of 32 

illustration  of 33 

sizes  of 32 

Drill  press  work 32-39 

centering  drill 39 

holding  work  in  vise 35 

holding  work  with  clamps.  35 

laying  off  centers  for  holes  34 

starting  drills 39 

Drilling,  brass 84 

fixed  depth .'  39 

holding  work  for 35 

holes  in  center  of  circle 39 

in  drill  press 34-38 

in  lathe,  with  twist  drill...  75 

with  flat  or  lathe  drill 67 

Drills,  flat  or  lathe 67 

use  of 68 

Drills,  twist 36 

centering  in  center  of  circle  39 

grinding 37 

grinding  for  brass 84 

how  held  in  drill  press 36 

how  held  in  lathe 75 

kinds  of 36 

sleeve  or  bushing  for 37 

socket  for  holding,  in  lathe  75 

speed  of " 38 

starting 39 

Driving  fit 78 

End  mill,  illustration  of 99 

End  mill  work 99-101 

clamping  work 100 

depth  of  cut 100 

direction  of  feed 101 

milling  recess 99 

milling  slot 99 

rate  of  feed 101 

speed  of  cutter 100 


Feeds,  rate  of,  for  lathe  work. .     90 

for  milling  cutter 97,  101 

shaper  work 90 

Files,  cut  of 11 

hand 11 

lathe 11 

size  of 11 

type  or  shape 11 

Filing,  flat  surface 12 

in  lathe  55 

Finishing  corners,  lathe  work. .     77 
shaper  work   29-30 

Finishing  end  of  cast  iron,  in 
lathe 73 

Finishing,  outside  of  cast  iron, 
lathe  work 66-74 

Finishing,  outside  of  cast  iron, 
lathe  work 77-84 

Finishing  taper  or  angle 57 

inside  with  compound  rest.     74 
inside    without    compound 

rest 74 

outside  with  compound  rest    79 
outside   without  compound 

rest 79 

with  lathe  scraper 74 

Finishing  tool,  lathe 55 

Finishing  tool,  shaper 21 

Flat  drills,  use  of 67 

Force  fits 78 

Forming  tool,  lathe  work 87 

Forming    cutter,    milling    ma- 
chine     102 

Gage,  drill  grinding 38 

thread  and  center 58 

U.  S.  S.  thread 58 

Gang  milling 101 

cutting  speed, 102 

depth  of  cut, 102 

Gear  cutting,  see  spur  gear  cu.t- 
ting. 

Gear  tooth,  shape  of 108 

terms  of 107 

Gear  tooth  cutter 108 

Groove  cutter. .  .   102 


INDEX 


121 


Grinding,   chisels 10 

scrapers 15 

shaper  tools 22,    29 

threading  tool 59 

turning  tool 53 

twist  drill 37 

Hack-saw,  use  of 49 

Index  crank 104 

pin 104 

plate  103 

Indexing,  dividing  head 104,  112 

Inside  threading 73 

cause  of  threads  breaking..     73 

finishing   threads 73 

tool  for 73 

with  tap,  by  hand 41 

with  tap,  in  lathe 42 

Key  way  cutter 102 

Knurling  tool 83,    86 

Lathe,  description  of 46 

illustration  of 47,    60 

Lathe  work,  brass 84-87 

cast  iron 65-83 

steel '..46-65 

Lubricant,  use  of 57 

for   filing    13 

finishing  tools,  in  lathe.  . .     52 

reaming  77 

tapping    41 

thread  cutting  in  lathe. . .     57 

threading  with  die 44 

threading  with  tap 41 

Machine,  drilling 32 

Mandrel  or  arbor,  gear Ill 

making    of 78 

milling  machine Ill 

mounting  work  on 78 

use  of 77 

Micrometer  caliper 80 

description  of 80 

how  to  read 81 

use  of 80 

Milling,  flat  surface 94-98 

groove  or  key  way 102 

irregular  surface 102 

rack 113  • 

recess 99 

slot  99 

spur  gear 110 


Milling  machine 93 

arbor 95 

clamping  work  in 95 

cutter 95 

description  of 92 

direction  of  feed 97 

direction  of  cutter  rotation  96 

finishing  cut  in 97 

illustration  of 93 

object   of  grinding  casting 

before  milling 94 

rate  of  feed 97 

roughing  cut 97 

speed  of  cutter 96 

vise  for 94 

Milling  machine  cutters 

arbor  for 95 

concave  102 

convex 102 

direction  of  feed  for 97 

direction  of  rotation 96 

end  mill 99 

feed  for,  rate  of 97,  101 

forming  102 

for  flat   surface 95 

gear  tooth 108 

grooves  or  key  way 102 

keyway 102 

rack   113 

recess 99 

side  cutting 101 

slots   99 

speed  of. 96,  100 

spiral  mill 95 

spur  gear 108 

Parallels,  use  of 26,  35,  95 

Pitch,  diametral 107 

of  gear  teeth 107 

of  screw 58 

Polishing  in  lathe 65,  75 

Questions  31,  91,  115 

Rack 106 

cutting  a 112 

holding  the 113 

spacing  the  teeth 113 

table  of  pitches  for 113 

Reamers,  rose,  advantage  of...  76 

shell  71 

use  of 72 


122 


INDEX 


Reaming  71 

speed  of  lathe  for 73 

with  rose  reamer 76 

with  shell  reamer 71 

Rose  reamer,  advantage  of 76 

use  of 76 

Roughing   inside   of   cast   iron, 

in  lathe 68 

advantage  of 68 

use  of  boring  bar 69 

use  of  flat  drill 68 

Scraper,  brass 87 

hand 16 

lathe 74 

Scraping,  flat  surface 13 

in  lathe 74 

in  vise 14 

Screw  cutting,  see  Thread  Cut- 
ting. 

Shaper    tools,    for  cutting   an- 
gles  27,  29 

finishing 21 

roughing 21 

survey    of 88 

Shaper,  description  of 18 

illustration  of 19 

size  of 18 

Shaper  work 

clamping  work  in  vise.. 20,  26 

depth  of  finishing  cut 23 

depth  of  roughing  cut 21 

direction  of  feed  fo/  finish- 
ing tool 22 

filing  angles 30 

finishing  tool 21 

finishing  60°  angles 29 

finishing  90°  angles 29 

laying  off  outline  of  piece 

of  work 26 

planing  end  of  block 24  ' 

rate   of   feed    for   finishing 

tool 23 

rate  of  feed   for   roughing 

tool 22 

resetting  work 23 

roughing  out  of  angles. ...  27 

roughing  tool 21 

setting  finishing  tool 22 

setting  head,  clapper  box 
and  tool  for  cutting  an- 
gles   28 


testing  work  for  squareness    23 
to    prevent    corners    from 

breaking 25 

use  of  parallels 26 

Shell  reamer,  use  of 72 

Speed  of  milling  cutters 

96,  100,  102 

Speed  of  drills 38 

Speed  of  lathe,  for  brass 84 

cast  iron 68 

drilling 38 

filing    55 

knurling 83 

reaming 73,    76 

steel    53 

thread  cutting 61,    79 

Speed  of  shaper 23 

Spiral  milling  cutter 95 

Spur  gear 106 

circular  pitch 107 

cutter  for 108 

diametrical  pitch 107 

pitch  circle 107 

pitch  diameter 107 

range  of  cutters 108 

rules  for  computing 109 

shape  of  tooth 108 

Spur  gear  cutting 110 

centering  of  cutter 110 

depth  of  cut Ill 

indexing 112 

mounting  cutter 110 

mounting  gear  mandrel   in 

dividing  head Ill 

placing  gear  on  mandrel. . .   110 

selecting  cutter 110 

sequence  of  operations 110 

setting  the  index  crank 111 

setting  the  sector 112 

Spur  gear  and  rack 106 

Starting  drill  in  work 39 

Steel  turning , 49-65 

Stock  and  die 43 

hand  use 43 

use  in  lathe 44 

Surface  plate,  use  of 14 

Table,  drill  speeds 38 

diametrical     and     circular 

pitches 113 

range  of  gear  tooth  cutters.  108 
Taps,  plug,  bottoming,  taper ...  40 
Taper  turning 57 


INDEX 


123 


Tapping,  brass 85 

cast  iron 41 

hand 41 

lathe 42 

lubricant  for 41 

square  or  true 41 

Threads,  lead  of 58 

pitch  of....... 58 

gage  for  grinding  tool  for.  58 

Thread  cutting,  brass 85 

cast  iron 65-83 

steel    56-65 

tool  for  outside 59 

tool  for  inside 73 

with  die  by  hand 43 

with  die  in  lathe 44 

with  tap  by  hand 40 

with  tap  in  lathe 42 

Thread  cutting  in  lathe 56-80 

boring  bar  for 73 

chamfering 62 

finishing  side  of  thread. ...  63 

grinding  tool  for 59 

how  to  reset  tool 65 

setting  tool 59 

speed  of  lathe. 61 

to  set  change  gears,  for...  61 

use  of  adjustable  stop 62 

use  of  die  for 44 

use  of  tap  for 42 

Thread    gage 58 

tool  59 

Tools,  lathe  and  shaper,  survey 

of 88 

Tools    for   lathe 50-84 

angle  cutting 74,  80 

brass  turning 84 

boring  bar 70 

centering  50 


corner  cutting 77 

cutting-off 57 

end  cutting 80 

flat   drill 68 

knurling 83 

rose  reamer 77 

roughing  or  turning 52 

scraper 74 

shell  reamer 71 

side  cutting  tool 52 

survey  of 33 

threading  tool .58-59 

twist  drill 75 

Tools    for    shaper,    see    Shaper 
Tools. 

Tools   for  vise  work,  see  Vise 
Work. 

Turning  angles 74,  80 

Turning,  brass 84 

cast  iron 55.84 

steel  shaft 49-53 

Turning    taper,    by    off-setting 

lathe  center 57 

with  compound  rest 74,  79 

Twist  drills,  see  Drills. 

Universal  chuck,  use  of 66 

Vise,   drill    '  35 

milling  machine 94 

shaper 19,  20 

Vise  work.... 9,  41,  43 

chipping 9 

filing 12 

laying  off  angles  for  shaper 

work 26 

laying  off  centers  for  drill- 
ing   34 

scraping 13 

thread  cutting  with  die.. .  .43-44 

thread  cutting  with  tap.  .41,  42 


Elementary  Forge  Practice 

By  ROBERT  H.  HARCOURT 
Instructor  in  Forge  Practice,  Leland  Stanford,  Junior,  University 

A  Text  for  High,  Vocational  and  Technical  Schools 

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815964 


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UNIVERSITY  OF  CAUFORNIA  LIBRARY 


